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diff --git a/lib/libUPnP/Neptune/Source/Tests/Xml1/big.xml b/lib/libUPnP/Neptune/Source/Tests/Xml1/big.xml new file mode 100644 index 0000000..ef590ac --- /dev/null +++ b/lib/libUPnP/Neptune/Source/Tests/Xml1/big.xml @@ -0,0 +1,3277 @@ +<?xml version="1.0" encoding="iso-8859-1"?> +<!DOCTYPE spec PUBLIC "-//W3C//DTD Specification V2.1//EN" + "http://www.w3.org/XML/1998/06/xmlspec-v21.dtd" [ +<!--ArborText, Inc., 1988-2000, v.4002--> +<!ENTITY http-ident "http://www.w3.org/TR/2000/REC-xml"> +<!ENTITY draft.month "October"> +<!ENTITY draft.day "6"> +<!ENTITY iso6.doc.date "20001006"> +<!ENTITY draft.year "2000"> +<!ENTITY versionOfXML "1.0"> +<!ENTITY pio "'<?xml'"> +<!ENTITY doc.date "10 February 1998"> +<!ENTITY w3c.doc.date "02-Feb-1998"> +<!ENTITY WebSGML "WebSGML Adaptations Annex to ISO 8879"> +<!ENTITY pic "'?>'"> +<!ENTITY br "\n"> +<!ENTITY cellback "#c0d9c0"> +<!ENTITY mdash "--"> +<!ENTITY com "--"> +<!ENTITY como "--"> +<!ENTITY comc "--"> +<!ENTITY hcro "&#x"> +<!ENTITY nbsp " "> +<!ENTITY magicents "<code>amp</code>, +<code>lt</code>, +<code>gt</code>, +<code>apos</code>, +<code>quot</code>"> +<!ENTITY doc.audience "public review and discussion"> +<!ENTITY doc.distribution "may be distributed freely, as long as +all text and legal notices remain intact"> +]> +<spec w3c-doctype="rec"> +<!-- +Notes on preparation of the Second Edition: + +- Worked from http://www.w3.org/XML/xml-19980210-errata. +- Changed DTD reference to point to V2.1 of XMLspec. +- Moved version number from <title> to <version> element and + added "second edition" wording. Mentioned edition information + in status. +- Removed bgcolor="&cellback;" attributes from all <td> + elements because that attribute is not in the current table model. +- Reversed status and abstract, so that abstract is first, according + to W3C guidelines. +- Changed some <emph>s to <titleref>s in bibliography. +- Changed some <code>s to <at> etc. throughout; where used <attval>, + removed existing <quote>s because the stylesheet produces them. +- Removed some spurious spaces. +- Added affiliation markup to the original member list. +- Added commas between individual <thisver> elements, because + whitespace is now significant there. +- Moved <eg>s, <scrap>s, and lists outside of <p>s for cleaner HTML + conversion. +- Revised Status section to reflect new status. +- Fixed all titleref hrefs so they get transformed properly; at + next revision, these all probably need to be changed to some + other markup. +- Incorporated all errata (barring obsoleted and invalid ones); + added links to the errata document with <loc role="erratumref"> + elements; used diff="{add|chg|del}" attribute. This version + expects that the official HTML output will have diff="del" + elements suppressed. +--> +<header> +<title>Extensible Markup Language (XML)</title> +<version>1.0 (Second Edition)</version> +<w3c-designation>REC-xml-&iso6.doc.date;</w3c-designation> +<w3c-doctype>W3C Recommendation</w3c-doctype> +<pubdate><day>&draft.day;</day><month>&draft.month;</month><year>&draft.year;</year> +</pubdate> +<publoc><loc href="&http-ident;-&iso6.doc.date;">&http-ident;-&iso6.doc.date;</loc> +(<loc href="&http-ident;-&iso6.doc.date;.html">XHTML</loc>, <loc href="&http-ident;-&iso6.doc.date;.xml">XML</loc>, <loc +href="&http-ident;-&iso6.doc.date;.pdf">PDF</loc>, <loc href="&http-ident;-&iso6.doc.date;-review.html">XHTML +review version</loc> with color-coded revision indicators)</publoc> +<latestloc><loc href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</loc></latestloc> +<prevlocs><loc href="http://www.w3.org/TR/2000/WD-xml-2e-20000814"> http://www.w3.org/TR/2000/WD-xml-2e-20000814</loc> +<loc href="http://www.w3.org/TR/1998/REC-xml-19980210"> http://www.w3.org/TR/1998/REC-xml-19980210</loc><!-- +<loc href='http://www.w3.org/TR/PR-xml-971208'> +http://www.w3.org/TR/PR-xml-971208</loc> +<loc href='http://www.w3.org/TR/WD-xml-961114'> +http://www.w3.org/TR/WD-xml-961114</loc> +<loc href='http://www.w3.org/TR/WD-xml-lang-970331'> +http://www.w3.org/TR/WD-xml-lang-970331</loc> +<loc href='http://www.w3.org/TR/WD-xml-lang-970630'> +http://www.w3.org/TR/WD-xml-lang-970630</loc> +<loc href='http://www.w3.org/TR/WD-xml-970807'> +http://www.w3.org/TR/WD-xml-970807</loc> +<loc href='http://www.w3.org/TR/WD-xml-971117'> +http://www.w3.org/TR/WD-xml-971117</loc>--> </prevlocs> +<authlist> +<author role="1e"><name>Tim Bray</name><affiliation>Textuality and Netscape</affiliation> +<email href="mailto:tbray@textuality.com">tbray@textuality.com</email></author> +<author role="1e"><name>Jean Paoli</name><affiliation>Microsoft</affiliation> +<email href="mailto:jeanpa@microsoft.com">jeanpa@microsoft.com</email></author> +<author role="1e" diff="chg"><name>C. M. Sperberg-McQueen</name><affiliation>University +of Illinois at Chicago and Text Encoding Initiative</affiliation><email href="mailto:cmsmcq@uic.edu">cmsmcq@uic.edu</email> +</author> +<author role="2e" diff="add"><name>Eve Maler</name><affiliation>Sun Microsystems, +Inc.</affiliation><email href="mailto:elm@east.sun.com">eve.maler@east.sun.com</email> +</author> +</authlist> +<abstract> +<p>The Extensible Markup Language (XML) is a subset of SGML that is completely +described in this document. Its goal is to enable generic SGML to be served, +received, and processed on the Web in the way that is now possible with HTML. +XML has been designed for ease of implementation and for interoperability +with both SGML and HTML.</p> +</abstract> +<status> +<p>This document has been reviewed by W3C Members and other interested parties +and has been endorsed by the Director as a W3C Recommendation. It is a stable +document and may be used as reference material or cited as a normative reference +from another document. W3C's role in making the Recommendation is to draw +attention to the specification and to promote its widespread deployment. This +enhances the functionality and interoperability of the Web.</p> +<p>This document specifies a syntax created by subsetting an existing, widely +used international text processing standard (Standard Generalized Markup Language, +ISO 8879:1986(E) as amended and corrected) for use on the World Wide Web. +It is a product of the W3C XML Activity, details of which can be found at <loc +href="http://www.w3.org/XML/">http://www.w3.org/XML</loc>. <phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E100">[E100]</loc> +The English version of this specification is the only normative version. However, +for translations of this document, see <loc href="http://www.w3.org/XML/#trans">http://www.w3.org/XML/#trans</loc>. </phrase>A +list of current W3C Recommendations and other technical documents can be found +at <loc href="http://www.w3.org/TR/">http://www.w3.org/TR</loc>.</p> +<p diff="del"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</loc>This +specification uses the term URI, which is defined by <bibref ref="Berners-Lee"/>, +a work in progress expected to update <bibref ref="RFC1738"/> and <bibref +ref="RFC1808"/>.</p> +<p diff="add">This second edition is <emph>not</emph> a new version of XML (first published 10 February 1998); +it merely incorporates the changes dictated by the first-edition errata (available +at <loc href="http://www.w3.org/XML/xml-19980210-errata">http://www.w3.org/XML/xml-19980210-errata</loc>) +as a convenience to readers. The errata list for this second edition is available +at <loc href="http://www.w3.org/XML/xml-V10-2e-errata">http://www.w3.org/XML/xml-V10-2e-errata</loc>.</p> +<p>Please report errors in this document to <loc href="mailto:xml-editor@w3.org">xml-editor@w3.org</loc><phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E101">[E101]</loc>; <loc +href="http://lists.w3.org/Archives/Public/xml-editor">archives</loc> are available</phrase>.</p> +<note diff="add"> +<p>C. M. Sperberg-McQueen's affiliation has changed since the publication +of the first edition. He is now at the World Wide Web Consortium, and can +be contacted at <loc href="mailto:cmsmcq@w3.org">cmsmcq@w3.org</loc>.</p> +</note> +</status> +<pubstmt> +<p>Chicago, Vancouver, Mountain View, et al.: World-Wide Web Consortium, XML +Working Group, 1996, 1997, 2000.</p> +</pubstmt> +<sourcedesc> +<p>Created in electronic form.</p> +</sourcedesc> +<langusage> +<language id="EN">English</language> +<language id="ebnf">Extended Backus-Naur Form (formal grammar)</language> +</langusage> +<revisiondesc> +<slist> +<sitem>1997-12-03 : CMSMcQ : yet further changes</sitem> +<sitem>1997-12-02 : TB : further changes (see TB to XML WG, 2 December 1997)</sitem> +<sitem>1997-12-02 : CMSMcQ : deal with as many corrections and comments from +the proofreaders as possible: entify hard-coded document date in pubdate element, +change expansion of entity WebSGML, update status description as per Dan Connolly +(am not sure about refernece to Berners-Lee et al.), add 'The' to abstract +as per WG decision, move Relationship to Existing Standards to back matter +and combine with References, re-order back matter so normative appendices +come first, re-tag back matter so informative appendices are tagged informdiv1, +remove XXX XXX from list of 'normative' specs in prose, move some references +from Other References to Normative References, add RFC 1738, 1808, and 2141 +to Other References (they are not normative since we do not require the processor +to enforce any rules based on them), add reference to 'Fielding draft' (Berners-Lee +et al.), move notation section to end of body, drop URIchar non-terminal and +use SkipLit instead, lose stray reference to defunct nonterminal 'markupdecls', +move reference to Aho et al. into appendix (Tim's right), add prose note saying +that hash marks and fragment identifiers are NOT part of the URI formally +speaking, and are NOT legal in system identifiers (processor 'may' signal +an error). Work through: Tim Bray reacting to James Clark, Tim Bray on his +own, Eve Maler, NOT DONE YET: change binary / text to unparsed / parsed. handle +James's suggestion about < in attriubte values uppercase hex characters, +namechar list, </sitem> +<sitem>1997-12-01 : JB : add some column-width parameters</sitem> +<sitem>1997-12-01 : CMSMcQ : begin round of changes to incorporate recent +WG decisions and other corrections: binding sources of character encoding +info (27 Aug / 3 Sept), correct wording of Faust quotation (restore dropped +line), drop SDD from EncodingDecl, change text at version number 1.0, drop +misleading (wrong!) sentence about ignorables and extenders, modify definition +of PCData to make bar on msc grammatical, change grammar's handling of internal +subset (drop non-terminal markupdecls), change definition of includeSect to +allow conditional sections, add integral-declaration constraint on internal +subset, drop misleading / dangerous sentence about relationship of entities +with system storage objects, change table body tag to htbody as per EM change +to DTD, add rule about space normalization in public identifiers, add description +of how to generate our name-space rules from Unicode character database (needs +further work!). </sitem> +<sitem>1997-10-08 : TB : Removed %-constructs again, new rules for PE appearance.</sitem> +<sitem>1997-10-01 : TB : Case-sensitive markup; cleaned up element-type defs, +lotsa little edits for style</sitem> +<sitem>1997-09-25 : TB : Change to elm's new DTD, with substantial detail +cleanup as a side-effect</sitem> +<sitem>1997-07-24 : CMSMcQ : correct error (lost *) in definition of ignoreSectContents +(thanks to Makoto Murata)</sitem> +<sitem>Allow all empty elements to have end-tags, consistent with SGML TC +(as per JJC).</sitem> +<sitem>1997-07-23 : CMSMcQ : pre-emptive strike on pending corrections: introduce +the term 'empty-element tag', note that all empty elements may use it, and +elements declared EMPTY must use it. Add WFC requiring encoding decl to come +first in an entity. Redefine notations to point to PIs as well as binary entities. +Change autodetection table by removing bytes 3 and 4 from examples with Byte +Order Mark. Add content model as a term and clarify that it applies to both +mixed and element content. </sitem> +<sitem>1997-06-30 : CMSMcQ : change date, some cosmetic changes, changes to +productions for choice, seq, Mixed, NotationType, Enumeration. Follow James +Clark's suggestion and prohibit conditional sections in internal subset. TO +DO: simplify production for ignored sections as a result, since we don't need +to worry about parsers which don't expand PErefs finding a conditional section.</sitem> +<sitem>1997-06-29 : TB : various edits</sitem> +<sitem>1997-06-29 : CMSMcQ : further changes: Suppress old FINAL EDIT comments +and some dead material. Revise occurrences of % in grammar to exploit Henry +Thompson's pun, especially markupdecl and attdef. Remove RMD requirement relating +to element content (?). </sitem> +<sitem>1997-06-28 : CMSMcQ : Various changes for 1 July draft: Add text for +draconian error handling (introduce the term Fatal Error). RE deleta est (changing +wording from original announcement to restrict the requirement to validating +parsers). Tag definition of validating processor and link to it. Add colon +as name character. Change def of %operator. Change standard definitions of +lt, gt, amp. Strip leading zeros from #x00nn forms.</sitem> +<sitem>1997-04-02 : CMSMcQ : final corrections of editorial errors found in +last night's proofreading. Reverse course once more on well-formed: Webster's +Second hyphenates it, and that's enough for me.</sitem> +<sitem>1997-04-01 : CMSMcQ : corrections from JJC, EM, HT, and self</sitem> +<sitem>1997-03-31 : Tim Bray : many changes</sitem> +<sitem>1997-03-29 : CMSMcQ : some Henry Thompson (on entity handling), some +Charles Goldfarb, some ERB decisions (PE handling in miscellaneous declarations. +Changed Ident element to accept def attribute. Allow normalization of Unicode +characters. move def of systemliteral into section on literals.</sitem> +<sitem>1997-03-28 : CMSMcQ : make as many corrections as possible, from Terry +Allen, Norbert Mikula, James Clark, Jon Bosak, Henry Thompson, Paul Grosso, +and self. Among other things: give in on "well formed" (Terry is right), tentatively +rename QuotedCData as AttValue and Literal as EntityValue to be more informative, +since attribute values are the <emph>only</emph> place QuotedCData was used, +and vice versa for entity text and Literal. (I'd call it Entity Text, but +8879 uses that name for both internal and external entities.)</sitem> +<sitem>1997-03-26 : CMSMcQ : resynch the two forks of this draft, reapply +my changes dated 03-20 and 03-21. Normalize old 'may not' to 'must not' except +in the one case where it meant 'may or may not'.</sitem> +<sitem>1997-03-21 : TB : massive changes on plane flight from Chicago to Vancouver</sitem> +<sitem>1997-03-21 : CMSMcQ : correct as many reported errors as possible. </sitem> +<sitem>1997-03-20 : CMSMcQ : correct typos listed in CMSMcQ hand copy of spec.</sitem> +<sitem>1997-03-20 : CMSMcQ : cosmetic changes preparatory to revision for +WWW conference April 1997: restore some of the internal entity references +(e.g. to docdate, etc.), change character xA0 to &nbsp; and define nbsp +as &#160;, and refill a lot of paragraphs for legibility.</sitem> +<sitem>1996-11-12 : CMSMcQ : revise using Tim's edits: Add list type of NUMBERED +and change most lists either to BULLETS or to NUMBERED. Suppress QuotedNames, +Names (not used). Correct trivial-grammar doc type decl. Rename 'marked section' +as 'CDATA section' passim. Also edits from James Clark: Define the set of +characters from which [^abc] subtracts. Charref should use just [0-9] not +Digit. Location info needs cleaner treatment: remove? (ERB question). One +example of a PI has wrong pic. Clarify discussion of encoding names. Encoding +failure should lead to unspecified results; don't prescribe error recovery. +Don't require exposure of entity boundaries. Ignore white space in element +content. Reserve entity names of the form u-NNNN. Clarify relative URLs. And +some of my own: Correct productions for content model: model cannot consist +of a name, so "elements ::= cp" is no good. </sitem> +<sitem>1996-11-11 : CMSMcQ : revise for style. Add new rhs to entity declaration, +for parameter entities.</sitem> +<sitem>1996-11-10 : CMSMcQ : revise for style. Fix / complete section on names, +characters. Add sections on parameter entities, conditional sections. Still +to do: Add compatibility note on deterministic content models. Finish stylistic +revision.</sitem> +<sitem>1996-10-31 : TB : Add Entity Handling section</sitem> +<sitem>1996-10-30 : TB : Clean up term & termdef. Slip in ERB decision +re EMPTY.</sitem> +<sitem>1996-10-28 : TB : Change DTD. Implement some of Michael's suggestions. +Change comments back to //. Introduce language for XML namespace reservation. +Add section on white-space handling. Lots more cleanup.</sitem> +<sitem>1996-10-24 : CMSMcQ : quick tweaks, implement some ERB decisions. Characters +are not integers. Comments are /* */ not //. Add bibliographic refs to 10646, +HyTime, Unicode. Rename old Cdata as MsData since it's <emph>only</emph> seen +in marked sections. Call them attribute-value pairs not name-value pairs, +except once. Internal subset is optional, needs '?'. Implied attributes should +be signaled to the app, not have values supplied by processor.</sitem> +<sitem>1996-10-16 : TB : track down & excise all DSD references; introduce +some EBNF for entity declarations.</sitem> +<sitem>1996-10-?? : TB : consistency check, fix up scraps so they all parse, +get formatter working, correct a few productions.</sitem> +<sitem>1996-10-10/11 : CMSMcQ : various maintenance, stylistic, and organizational +changes: Replace a few literals with xmlpio and pic entities, to make them +consistent and ensure we can change pic reliably when the ERB votes. Drop +paragraph on recognizers from notation section. Add match, exact match to +terminology. Move old 2.2 XML Processors and Apps into intro. Mention comments, +PIs, and marked sections in discussion of delimiter escaping. Streamline discussion +of doctype decl syntax. Drop old section of 'PI syntax' for doctype decl, +and add section on partial-DTD summary PIs to end of Logical Structures section. +Revise DSD syntax section to use Tim's subset-in-a-PI mechanism.</sitem> +<sitem>1996-10-10 : TB : eliminate name recognizers (and more?)</sitem> +<sitem>1996-10-09 : CMSMcQ : revise for style, consistency through 2.3 (Characters)</sitem> +<sitem>1996-10-09 : CMSMcQ : re-unite everything for convenience, at least +temporarily, and revise quickly</sitem> +<sitem>1996-10-08 : TB : first major homogenization pass</sitem> +<sitem>1996-10-08 : TB : turn "current" attribute on div type into CDATA</sitem> +<sitem>1996-10-02 : TB : remould into skeleton + entities</sitem> +<sitem>1996-09-30 : CMSMcQ : add a few more sections prior to exchange with +Tim.</sitem> +<sitem>1996-09-20 : CMSMcQ : finish transcribing notes.</sitem> +<sitem>1996-09-19 : CMSMcQ : begin transcribing notes for draft.</sitem> +<sitem>1996-09-13 : CMSMcQ : made outline from notes of 09-06, do some housekeeping</sitem> +</slist> +</revisiondesc> +</header> +<body> +<div1 id="sec-intro"> +<head>Introduction</head> +<p>Extensible Markup Language, abbreviated XML, describes a class of data +objects called <termref def="dt-xml-doc">XML documents</termref> and partially +describes the behavior of computer programs which process them. XML is an +application profile or restricted form of SGML, the Standard Generalized Markup +Language <bibref ref="ISO8879"/>. By construction, XML documents are conforming +SGML documents.</p> +<p>XML documents are made up of storage units called <termref def="dt-entity">entities</termref>, +which contain either parsed or unparsed data. Parsed data is made up of <termref +def="dt-character">characters</termref>, some of which form <termref def="dt-chardata">character +data</termref>, and some of which form <termref def="dt-markup">markup</termref>. +Markup encodes a description of the document's storage layout and logical +structure. XML provides a mechanism to impose constraints on the storage layout +and logical structure.</p> +<p><termdef id="dt-xml-proc" term="XML Processor">A software module called +an <term>XML processor</term> is used to read XML documents and provide access +to their content and structure.</termdef> <termdef id="dt-app" term="Application">It +is assumed that an XML processor is doing its work on behalf of another module, +called the <term>application</term>.</termdef> This specification describes +the required behavior of an XML processor in terms of how it must read XML +data and the information it must provide to the application.</p> +<div2 id="sec-origin-goals"> +<head>Origin and Goals</head> +<p>XML was developed by an XML Working Group (originally known as the SGML +Editorial Review Board) formed under the auspices of the World Wide Web Consortium +(W3C) in 1996. It was chaired by Jon Bosak of Sun Microsystems with the active +participation of an XML Special Interest Group (previously known as the SGML +Working Group) also organized by the W3C. The membership of the XML Working +Group is given in an appendix. Dan Connolly served as the WG's contact with +the W3C.</p> +<p>The design goals for XML are:</p> +<olist> +<item><p>XML shall be straightforwardly usable over the Internet.</p></item> +<item><p>XML shall support a wide variety of applications.</p></item> +<item><p>XML shall be compatible with SGML.</p></item> +<item><p>It shall be easy to write programs which process XML documents.</p> +</item> +<item><p>The number of optional features in XML is to be kept to the absolute +minimum, ideally zero.</p></item> +<item><p>XML documents should be human-legible and reasonably clear.</p></item> +<item><p>The XML design should be prepared quickly.</p></item> +<item><p>The design of XML shall be formal and concise.</p></item> +<item><p>XML documents shall be easy to create.</p></item> +<item><p>Terseness in XML markup is of minimal importance.</p></item> +</olist> +<p>This specification, together with associated standards (Unicode and ISO/IEC +10646 for characters, Internet RFC 1766 for language identification tags, +ISO 639 for language name codes, and ISO 3166 for country name codes), provides +all the information necessary to understand XML Version &versionOfXML; and +construct computer programs to process it.</p> +<p>This version of the XML specification <!-- is for &doc.audience;.--> &doc.distribution;.</p> +</div2> +<div2 id="sec-terminology"> +<head>Terminology</head> +<p>The terminology used to describe XML documents is defined in the body of +this specification. The terms defined in the following list are used in building +those definitions and in describing the actions of an XML processor: <glist> +<gitem><label>may</label> +<def> +<p><termdef id="dt-may" term="May">Conforming documents and XML processors +are permitted to but need not behave as described.</termdef></p> +</def></gitem> +<gitem><label>must</label> +<def> +<p><termdef id="dt-must" term="Must">Conforming documents and XML processors +are required to behave as described; otherwise they are in error. <!-- do NOT change this! this is what defines a violation of +a 'must' clause as 'an error'. -MSM --></termdef></p> +</def></gitem> +<gitem><label>error</label> +<def> +<p><termdef id="dt-error" term="Error">A violation of the rules of this specification; +results are undefined. Conforming software may detect and report an error +and may recover from it.</termdef></p> +</def></gitem> +<gitem><label>fatal error</label> +<def> +<p><termdef id="dt-fatal" term="Fatal Error">An error which a conforming <termref +def="dt-xml-proc">XML processor</termref> must detect and report to the application. +After encountering a fatal error, the processor may continue processing the +data to search for further errors and may report such errors to the application. +In order to support correction of errors, the processor may make unprocessed +data from the document (with intermingled character data and markup) available +to the application. Once a fatal error is detected, however, the processor +must not continue normal processing (i.e., it must not continue to pass character +data and information about the document's logical structure to the application +in the normal way).</termdef></p> +</def></gitem> +<gitem><label>at user option</label> +<def> +<p><termdef id="dt-atuseroption" term="At user option">Conforming software +may or must (depending on the modal verb in the sentence) behave as described; +if it does, it must provide users a means to enable or disable the behavior +described.</termdef></p> +</def></gitem> +<gitem><label>validity constraint</label> +<def> +<p><termdef id="dt-vc" term="Validity constraint">A rule which applies to +all <termref def="dt-valid">valid</termref> XML documents. Violations of validity +constraints are errors; they must, at user option, be reported by <termref +def="dt-validating">validating XML processors</termref>.</termdef></p> +</def></gitem> +<gitem><label>well-formedness constraint</label> +<def> +<p><termdef id="dt-wfc" term="Well-formedness constraint">A rule which applies +to all <termref def="dt-wellformed">well-formed</termref> XML documents. Violations +of well-formedness constraints are <termref def="dt-fatal">fatal errors</termref>.</termdef></p> +</def></gitem> +<gitem><label>match</label> +<def> +<p><termdef id="dt-match" term="match">(Of strings or names:) Two strings +or names being compared must be identical. Characters with multiple possible +representations in ISO/IEC 10646 (e.g. characters with both precomposed and +base+diacritic forms) match only if they have the same representation in both +strings. <phrase diff="del"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E85">[E85]</loc>At +user option, processors may normalize such characters to some canonical form. </phrase>No +case folding is performed. (Of strings and rules in the grammar:) A string +matches a grammatical production if it belongs to the language generated by +that production. (Of content and content models:) An element matches its declaration +when it conforms in the fashion described in the constraint <specref ref="elementvalid"/>.</termdef></p> +</def></gitem> +<gitem><label>for compatibility</label> +<def> +<p><termdef id="dt-compat" term="For Compatibility"><phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E87">[E87]</loc>Marks +a sentence describing</phrase> a feature of XML included solely to ensure +that XML remains compatible with SGML.</termdef></p> +</def></gitem> +<gitem><label>for interoperability</label> +<def> +<p><termdef id="dt-interop" term="For interoperability"><phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E87">[E87]</loc>Marks +a sentence describing</phrase> a non-binding recommendation included to increase +the chances that XML documents can be processed by the existing installed +base of SGML processors which predate the &WebSGML;.</termdef></p> +</def></gitem> +</glist></p> +</div2> +</div1> +<!-- &Docs; --> +<div1 id="sec-documents"> +<head>Documents</head> +<p><termdef id="dt-xml-doc" term="XML Document"> A data object is an <term>XML +document</term> if it is <termref def="dt-wellformed">well-formed</termref>, +as defined in this specification. A well-formed XML document may in addition +be <termref def="dt-valid">valid</termref> if it meets certain further constraints.</termdef></p> +<p>Each XML document has both a logical and a physical structure. Physically, +the document is composed of units called <termref def="dt-entity">entities</termref>. +An entity may <termref def="dt-entref">refer</termref> to other entities to +cause their inclusion in the document. A document begins in a <quote>root</quote> +or <termref def="dt-docent">document entity</termref>. Logically, the document +is composed of declarations, elements, comments, character references, and +processing instructions, all of which are indicated in the document by explicit +markup. The logical and physical structures must nest properly, as described +in <specref ref="wf-entities"/>.</p> +<div2 id="sec-well-formed"> +<head>Well-Formed XML Documents</head> +<p><termdef id="dt-wellformed" term="Well-Formed"> A textual object is a <term>well-formed</term> +XML document if:</termdef></p> +<olist> +<item><p>Taken as a whole, it matches the production labeled <nt def="NT-document">document</nt>.</p> +</item> +<item><p>It meets all the well-formedness constraints given in this specification.</p> +</item> +<item><p>Each of the <termref def="dt-parsedent">parsed entities</termref> +which is referenced directly or indirectly within the document is <termref +def="dt-wellformed">well-formed</termref>.</p></item> +</olist> +<scrap id="document" lang="ebnf"> +<head>Document</head> +<prod id="NT-document"> +<lhs>document</lhs><rhs><nt def="NT-prolog">prolog</nt> <nt def="NT-element">element</nt> <nt +def="NT-Misc">Misc</nt>*</rhs> +</prod> +</scrap> +<p>Matching the <nt def="NT-document">document</nt> production implies that:</p> +<olist> +<item><p>It contains one or more <termref def="dt-element">elements</termref>.</p> +</item> +<!--* N.B. some readers (notably JC) find the following +paragraph awkward and redundant. I agree it's logically redundant: +it *says* it is summarizing the logical implications of +matching the grammar, and that means by definition it's +logically redundant. I don't think it's rhetorically +redundant or unnecessary, though, so I'm keeping it. It +could however use some recasting when the editors are feeling +stronger. -MSM *--> +<item><p><termdef id="dt-root" term="Root Element">There is exactly one element, +called the <term>root</term>, or document element, no part of which appears +in the <termref def="dt-content">content</termref> of any other element.</termdef> <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E17">[E17]</loc>For +all other elements, if the <termref def="dt-stag">start-tag</termref> is in +the content of another element, the <termref def="dt-etag">end-tag</termref> +is in the content of the same element.</phrase> More simply stated, the elements, +delimited by start- and end-tags, nest properly within each other.</p></item> +</olist> +<p><termdef id="dt-parentchild" term="Parent/Child">As a consequence of this, +for each non-root element <el>C</el> in the document, there is one other element <el>P</el> +in the document such that <el>C</el> is in the content of <el>P</el>, but +is not in the content of any other element that is in the content of <el>P</el>. <el>P</el> +is referred to as the <term>parent</term> of <el>C</el>, and <el>C</el> as +a <term>child</term> of <el>P</el>.</termdef></p> +</div2> +<div2 id="charsets"> +<head>Characters</head> +<p><termdef id="dt-text" term="Text">A parsed entity contains <term>text</term>, +a sequence of <termref def="dt-character">characters</termref>, which may +represent markup or character data.</termdef> <termdef id="dt-character" term="Character">A <term>character</term> +is an atomic unit of text as specified by ISO/IEC 10646 <bibref ref="ISO10646"/> <phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc>(see +also <bibref ref="ISO10646-2000"/>)</phrase>. Legal characters are tab, carriage +return, line feed, and the legal <phrase diff="del"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E35">[E35]</loc>graphic </phrase>characters +of Unicode and ISO/IEC 10646. <phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E69">[E69]</loc>The +versions of these standards cited in <specref ref="sec-existing-stds"/> were +current at the time this document was prepared. New characters may be added +to these standards by amendments or new editions. Consequently, XML processors +must accept any character in the range specified for <nt def="NT-Char">Char</nt>.</phrase> +The use of <quote>compatibility characters</quote>, as defined in section +6.8 of <bibref ref="Unicode"/> <phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc>(see +also D21 in section 3.6 of <bibref ref="Unicode3"/>)</phrase>, is discouraged.</termdef></p> +<scrap id="char32" lang="ebnf"> +<head>Character Range</head> +<prodgroup pcw2="4" pcw4="17.5" pcw5="11"> +<prod id="NT-Char"> +<lhs>Char</lhs><rhs>#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]</rhs> +<com>any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.</com> +</prod> +</prodgroup></scrap> +<p>The mechanism for encoding character code points into bit patterns may +vary from entity to entity. All XML processors must accept the UTF-8 and UTF-16 +encodings of 10646; the mechanisms for signaling which of the two is in use, +or for bringing other encodings into play, are discussed later, in <specref +ref="charencoding"/>.</p> +<!-- +<p>Regardless of the specific encoding used, any character in +the ISO/IEC 10646 character set may be referred to by the decimal +or hexadecimal equivalent of its UCS-4 code value. +</p>--> +</div2> +<div2 id="sec-common-syn"> +<head>Common Syntactic Constructs</head> +<p>This section defines some symbols used widely in the grammar.</p> +<p><nt def="NT-S">S</nt> (white space) consists of one or more space (#x20) +characters, carriage returns, line feeds, or tabs.</p> +<scrap id="white" lang="ebnf"> +<head>White Space</head> +<prodgroup pcw2="4" pcw4="17.5" pcw5="11"> +<prod id="NT-S"> +<lhs>S</lhs><rhs>(#x20 | #x9 | #xD | #xA)+</rhs> +</prod> +</prodgroup></scrap> +<p>Characters are classified for convenience as letters, digits, or other +characters. <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E30">[E30]</loc>A +letter consists of an alphabetic or syllabic base character or an ideographic +character.</phrase> Full definitions of the specific characters in each class +are given in <specref ref="CharClasses"/>.</p> +<p><termdef id="dt-name" term="Name">A <term>Name</term> is a token beginning +with a letter or one of a few punctuation characters, and continuing with +letters, digits, hyphens, underscores, colons, or full stops, together known +as name characters.</termdef> Names beginning with the string <quote><code>xml</code></quote>, +or any string which would match <code>(('X'|'x') ('M'|'m') ('L'|'l'))</code>, +are reserved for standardization in this or future versions of this specification.</p> +<note> +<p diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E98">[E98]</loc>The +Namespaces in XML Recommendation <bibref ref="xml-names"/> assigns a meaning +to names containing colon characters. Therefore, authors should not use the +colon in XML names except for namespace purposes, but XML processors must +accept the colon as a name character.</p> +</note> +<p>An <nt def="NT-Nmtoken">Nmtoken</nt> (name token) is any mixture of name +characters.</p> +<scrap lang="ebnf"> +<head>Names and Tokens</head> +<prod id="NT-NameChar"> +<lhs>NameChar</lhs><rhs><nt def="NT-Letter">Letter</nt> | <nt def="NT-Digit">Digit</nt> +| '.' | '-' | '_' | ':' | <nt def="NT-CombiningChar">CombiningChar</nt> | <nt +def="NT-Extender">Extender</nt></rhs> +</prod> +<prod id="NT-Name"> +<lhs>Name</lhs><rhs>(<nt def="NT-Letter">Letter</nt> | '_' | ':') (<nt def="NT-NameChar">NameChar</nt>)*</rhs> +</prod> +<prod id="NT-Names"> +<lhs>Names</lhs><rhs><nt def="NT-Name">Name</nt> (<nt def="NT-S">S</nt> <nt +def="NT-Name">Name</nt>)*</rhs> +</prod> +<prod id="NT-Nmtoken"> +<lhs>Nmtoken</lhs><rhs>(<nt def="NT-NameChar">NameChar</nt>)+</rhs> +</prod> +<prod id="NT-Nmtokens"> +<lhs>Nmtokens</lhs><rhs><nt def="NT-Nmtoken">Nmtoken</nt> (<nt def="NT-S">S</nt> <nt +def="NT-Nmtoken">Nmtoken</nt>)*</rhs> +</prod> +</scrap> +<p>Literal data is any quoted string not containing the quotation mark used +as a delimiter for that string. Literals are used for specifying the content +of internal entities (<nt def="NT-EntityValue">EntityValue</nt>), the values +of attributes (<nt def="NT-AttValue">AttValue</nt>), and external identifiers +(<nt def="NT-SystemLiteral">SystemLiteral</nt>). Note that a <nt def="NT-SystemLiteral">SystemLiteral</nt> +can be parsed without scanning for markup.</p> +<scrap lang="ebnf"> +<head>Literals</head> +<prod id="NT-EntityValue"> +<lhs>EntityValue</lhs><rhs>'"' ([^%&"] | <nt def="NT-PEReference">PEReference</nt> +| <nt def="NT-Reference">Reference</nt>)* '"' </rhs> +<rhs>| "'" ([^%&'] | <nt def="NT-PEReference">PEReference</nt> | <nt +def="NT-Reference">Reference</nt>)* "'"</rhs> +</prod> +<prod id="NT-AttValue"> +<lhs>AttValue</lhs><rhs>'"' ([^<&"] | <nt def="NT-Reference">Reference</nt>)* +'"' </rhs> +<rhs>| "'" ([^<&'] | <nt def="NT-Reference">Reference</nt>)* +"'"</rhs> +</prod> +<prod id="NT-SystemLiteral"> +<lhs>SystemLiteral</lhs><rhs>('"' [^"]* '"') | ("'" [^']* "'") </rhs> +</prod> +<prod id="NT-PubidLiteral"> +<lhs>PubidLiteral</lhs><rhs>'"' <nt def="NT-PubidChar">PubidChar</nt>* '"' +| "'" (<nt def="NT-PubidChar">PubidChar</nt> - "'")* "'"</rhs> +</prod> +<prod id="NT-PubidChar"> +<lhs>PubidChar</lhs><rhs>#x20 | #xD | #xA | [a-zA-Z0-9] | [-'()+,./:=?;!*#@$_%]</rhs> +</prod> +</scrap> +<note diff="add"> +<p><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E72">[E72]</loc>Although +the <nt def="NT-EntityValue">EntityValue</nt> production allows the definition +of an entity consisting of a single explicit <code><</code> in the literal +(e.g., <code><!ENTITY mylt "<"></code>), it is strongly advised to avoid +this practice since any reference to that entity will cause a well-formedness +error.</p> +</note> +</div2> +<div2 id="syntax"> +<head>Character Data and Markup</head> +<p><termref def="dt-text">Text</termref> consists of intermingled <termref +def="dt-chardata">character data</termref> and markup. <termdef id="dt-markup" +term="Markup"><term>Markup</term> takes the form of <termref def="dt-stag">start-tags</termref>, <termref +def="dt-etag">end-tags</termref>, <termref def="dt-empty">empty-element tags</termref>, <termref +def="dt-entref">entity references</termref>, <termref def="dt-charref">character +references</termref>, <termref def="dt-comment">comments</termref>, <termref +def="dt-cdsection">CDATA section</termref> delimiters, <termref def="dt-doctype">document +type declarations</termref>, <termref def="dt-pi">processing instructions</termref>, <phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E89">[E89]</loc><nt +def="NT-XMLDecl">XML declarations</nt>, <nt def="NT-TextDecl">text declarations</nt>, +and any white space that is at the top level of the document entity (that +is, outside the document element and not inside any other markup).</phrase></termdef></p> +<p><termdef id="dt-chardata" term="Character Data">All text that is not markup +constitutes the <term>character data</term> of the document.</termdef></p> +<p>The ampersand character (&) and the left angle bracket (<) may appear +in their literal form <emph>only</emph> when used as markup delimiters, or +within a <termref def="dt-comment">comment</termref>, a <termref def="dt-pi">processing +instruction</termref>, or a <termref def="dt-cdsection">CDATA section</termref>.<phrase +diff="del"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E18">[E18]</loc>They +are also legal within the <termref def="dt-litentval">literal entity value</termref> +of an internal entity declaration; see <specref ref="wf-entities"/>.</phrase> <!-- FINAL EDIT: restore internal entity decl or leave it out. --> +If they are needed elsewhere, they must be <termref def="dt-escape">escaped</termref> +using either <termref def="dt-charref">numeric character references</termref> +or the strings <quote><code>&amp;</code></quote> and <quote><code>&lt;</code></quote> +respectively. The right angle bracket (>) may be represented using the string <quote><code>&gt;</code></quote>, +and must, <termref def="dt-compat">for compatibility</termref>, be escaped +using <quote><code>&gt;</code></quote> or a character reference when it +appears in the string <quote><code>]]></code></quote> in content, when +that string is not marking the end of a <termref def="dt-cdsection">CDATA +section</termref>.</p> +<p>In the content of elements, character data is any string of characters +which does not contain the start-delimiter of any markup. In a CDATA section, +character data is any string of characters not including the CDATA-section-close +delimiter, <quote><code>]]></code></quote>.</p> +<p>To allow attribute values to contain both single and double quotes, the +apostrophe or single-quote character (') may be represented as <quote><code>&apos;</code></quote>, +and the double-quote character (") as <quote><code>&quot;</code></quote>.</p> +<scrap lang="ebnf"> +<head>Character Data</head> +<prod id="NT-CharData"> +<lhs>CharData</lhs><rhs>[^<&]* - ([^<&]* ']]>' [^<&]*)</rhs> +</prod> +</scrap> +</div2> +<div2 id="sec-comments"> +<head>Comments</head> +<p><termdef id="dt-comment" term="Comment"><term>Comments</term> may appear +anywhere in a document outside other <termref def="dt-markup">markup</termref>; +in addition, they may appear within the document type declaration at places +allowed by the grammar. They are not part of the document's <termref def="dt-chardata">character +data</termref>; an XML processor may, but need not, make it possible for an +application to retrieve the text of comments. <termref def="dt-compat">For +compatibility</termref>, the string <quote><code>--</code></quote> (double-hyphen) +must not occur within comments.</termdef> <phrase diff="add"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E63">[E63]</loc>Parameter +entity references are not recognized within comments.</phrase></p> +<scrap lang="ebnf"> +<head>Comments</head> +<prod id="NT-Comment"> +<lhs>Comment</lhs><rhs>'<!--' ((<nt def="NT-Char">Char</nt> - '-') | ('-' +(<nt def="NT-Char">Char</nt> - '-')))* '-->'</rhs> +</prod> +</scrap> +<p>An example of a comment:</p> +<eg><!&como; declarations for <head> & <body> &comc;></eg> +<p diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E27">[E27]</loc>Note +that the grammar does not allow a comment ending in <code>---></code>. The +following example is <emph>not</emph> well-formed.</p> +<eg diff="add"><!-- B+, B, or B---></eg> +</div2> +<div2 id="sec-pi"> +<head>Processing Instructions</head> +<p><termdef id="dt-pi" term="Processing instruction"><term>Processing instructions</term> +(PIs) allow documents to contain instructions for applications.</termdef></p> +<scrap lang="ebnf"> +<head>Processing Instructions</head> +<prod id="NT-PI"> +<lhs>PI</lhs><rhs>'<?' <nt def="NT-PITarget">PITarget</nt> (<nt def="NT-S">S</nt> +(<nt def="NT-Char">Char</nt>* - (<nt def="NT-Char">Char</nt>* &pic; <nt def="NT-Char">Char</nt>*)))? &pic;</rhs> +</prod> +<prod id="NT-PITarget"> +<lhs>PITarget</lhs><rhs><nt def="NT-Name">Name</nt> - (('X' | 'x') ('M' | +'m') ('L' | 'l'))</rhs> +</prod> +</scrap> +<p>PIs are not part of the document's <termref def="dt-chardata">character +data</termref>, but must be passed through to the application. The PI begins +with a target (<nt def="NT-PITarget">PITarget</nt>) used to identify the application +to which the instruction is directed. The target names <quote><code>XML</code></quote>, <quote><code>xml</code></quote>, +and so on are reserved for standardization in this or future versions of this +specification. The XML <termref def="dt-notation">Notation</termref> mechanism +may be used for formal declaration of PI targets. <phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E63">[E63]</loc>Parameter +entity references are not recognized within processing instructions.</phrase></p> +</div2> +<div2 id="sec-cdata-sect"> +<head>CDATA Sections</head> +<p><termdef id="dt-cdsection" term="CDATA Section"><term>CDATA sections</term> +may occur anywhere character data may occur; they are used to escape blocks +of text containing characters which would otherwise be recognized as markup. +CDATA sections begin with the string <quote><code><![CDATA[</code></quote> +and end with the string <quote><code>]]></code></quote>:</termdef></p> +<scrap lang="ebnf"> +<head>CDATA Sections</head> +<prod id="NT-CDSect"> +<lhs>CDSect</lhs><rhs><nt def="NT-CDStart">CDStart</nt> <nt def="NT-CData">CData</nt> <nt +def="NT-CDEnd">CDEnd</nt></rhs> +</prod> +<prod id="NT-CDStart"> +<lhs>CDStart</lhs><rhs>'<![CDATA['</rhs> +</prod> +<prod id="NT-CData"> +<lhs>CData</lhs><rhs>(<nt def="NT-Char">Char</nt>* - (<nt def="NT-Char">Char</nt>* +']]>' <nt def="NT-Char">Char</nt>*)) </rhs> +</prod> +<prod id="NT-CDEnd"> +<lhs>CDEnd</lhs><rhs>']]>'</rhs> +</prod> +</scrap> +<p>Within a CDATA section, only the <nt def="NT-CDEnd">CDEnd</nt> string is +recognized as markup, so that left angle brackets and ampersands may occur +in their literal form; they need not (and cannot) be escaped using <quote><code>&lt;</code></quote> +and <quote><code>&amp;</code></quote>. CDATA sections cannot nest.</p> +<p>An example of a CDATA section, in which <quote><code><greeting></code></quote> +and <quote><code></greeting></code></quote> are recognized as <termref +def="dt-chardata">character data</termref>, not <termref def="dt-markup">markup</termref>:</p> +<eg><![CDATA[<greeting>Hello, world!</greeting>]]> </eg> +</div2> +<div2 id="sec-prolog-dtd"> +<head>Prolog and Document Type Declaration</head> +<p><termdef id="dt-xmldecl" term="XML Declaration">XML documents <phrase diff="chg"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E107">[E107]</loc>should</phrase> +begin with an <term>XML declaration</term> which specifies the version of +XML being used.</termdef> For example, the following is a complete XML document, <termref +def="dt-wellformed">well-formed</termref> but not <termref def="dt-valid">valid</termref>:</p> +<eg><![CDATA[<?xml version="1.0"?> <greeting>Hello, world!</greeting> ]]></eg> +<p>and so is this:</p> +<eg><![CDATA[<greeting>Hello, world!</greeting>]]></eg> +<p>The version number <quote><code>1.0</code></quote> should be used to indicate +conformance to this version of this specification; it is an error for a document +to use the value <quote><code>1.0</code></quote> if it does not conform to +this version of this specification. It is the intent of the XML working group +to give later versions of this specification numbers other than <quote><code>1.0</code></quote>, +but this intent does not indicate a commitment to produce any future versions +of XML, nor if any are produced, to use any particular numbering scheme. Since +future versions are not ruled out, this construct is provided as a means to +allow the possibility of automatic version recognition, should it become necessary. +Processors may signal an error if they receive documents labeled with versions +they do not support.</p> +<p>The function of the markup in an XML document is to describe its storage +and logical structure and to associate attribute-value pairs with its logical +structures. XML provides a mechanism, the <termref def="dt-doctype">document +type declaration</termref>, to define constraints on the logical structure +and to support the use of predefined storage units. <termdef id="dt-valid" +term="Validity">An XML document is <term>valid</term> if it has an associated +document type declaration and if the document complies with the constraints +expressed in it.</termdef></p> +<p>The document type declaration must appear before the first <termref def="dt-element">element</termref> +in the document.</p> +<scrap id="xmldoc" lang="ebnf"> +<head>Prolog</head> +<prodgroup pcw2="6" pcw4="17.5" pcw5="9"> +<prod id="NT-prolog"> +<lhs>prolog</lhs><rhs><nt def="NT-XMLDecl">XMLDecl</nt>? <nt def="NT-Misc">Misc</nt>* +(<nt def="NT-doctypedecl">doctypedecl</nt> <nt def="NT-Misc">Misc</nt>*)?</rhs> +</prod> +<prod id="NT-XMLDecl"> +<lhs>XMLDecl</lhs><rhs>&pio; <nt def="NT-VersionInfo">VersionInfo</nt> <nt +def="NT-EncodingDecl">EncodingDecl</nt>? <nt def="NT-SDDecl">SDDecl</nt>? <nt +def="NT-S">S</nt>? &pic;</rhs> +</prod> +<prod id="NT-VersionInfo" diff="chg"> +<lhs>VersionInfo</lhs><rhs><nt def="NT-S">S</nt> 'version' <nt def="NT-Eq">Eq</nt> +("'" <nt def="NT-VersionNum">VersionNum</nt> "'" | '"' <nt def="NT-VersionNum">VersionNum</nt> +'"')<com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E15">[E15]</loc></com></rhs> +</prod> +<prod id="NT-Eq"> +<lhs>Eq</lhs><rhs><nt def="NT-S">S</nt>? '=' <nt def="NT-S">S</nt>?</rhs> +</prod> +<prod id="NT-VersionNum"> +<lhs>VersionNum</lhs><rhs>([a-zA-Z0-9_.:] | '-')+</rhs> +</prod> +<prod id="NT-Misc"> +<lhs>Misc</lhs><rhs><nt def="NT-Comment">Comment</nt> | <nt def="NT-PI">PI</nt> +| <nt def="NT-S">S</nt></rhs> +</prod> +</prodgroup></scrap> +<p><termdef id="dt-doctype" term="Document Type Declaration">The XML <term>document +type declaration</term> contains or points to <termref def="dt-markupdecl">markup +declarations</termref> that provide a grammar for a class of documents. This +grammar is known as a document type definition, or <term>DTD</term>. The document +type declaration can point to an external subset (a special kind of <termref +def="dt-extent">external entity</termref>) containing markup declarations, +or can contain the markup declarations directly in an internal subset, or +can do both. The DTD for a document consists of both subsets taken together.</termdef></p> +<p><termdef id="dt-markupdecl" term="markup declaration"> A <term>markup declaration</term> +is an <termref def="dt-eldecl">element type declaration</termref>, an <termref +def="dt-attdecl">attribute-list declaration</termref>, an <termref def="dt-entdecl">entity +declaration</termref>, or a <termref def="dt-notdecl">notation declaration</termref>.</termdef> +These declarations may be contained in whole or in part within <termref def="dt-PE">parameter +entities</termref>, as described in the well-formedness and validity constraints +below. For <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E14">[E14]</loc>further</phrase> +information, see <specref ref="sec-physical-struct"/>.</p> +<scrap id="dtd" lang="ebnf"> +<head>Document Type Definition</head> +<prodgroup pcw2="6" pcw4="17.5" pcw5="9"> +<prod id="NT-doctypedecl" diff="chg"> +<lhs>doctypedecl</lhs><rhs>'<!DOCTYPE' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt> +(<nt def="NT-S">S</nt> <nt def="NT-ExternalID">ExternalID</nt>)? <nt def="NT-S">S</nt>? +('[' (<nt def="NT-markupdecl">markupdecl</nt> | <nt diff="chg" def="NT-DeclSep">DeclSep</nt>)* +']' <nt def="NT-S">S</nt>?)? '>'</rhs><vc def="vc-roottype"/><wfc def="ExtSubset" +diff="add"/><com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc></com> +</prod> +<prod id="NT-DeclSep" diff="add"> +<lhs>DeclSep</lhs><rhs><nt def="NT-PEReference">PEReference</nt> | <nt def="NT-S">S</nt></rhs> +<wfc def="PE-between-Decls" diff="add"/><com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc></com> +</prod> +<prod id="NT-markupdecl"> +<lhs>markupdecl</lhs><rhs><nt def="NT-elementdecl">elementdecl</nt> | <nt +def="NT-AttlistDecl">AttlistDecl</nt> | <nt def="NT-EntityDecl">EntityDecl</nt> +| <nt def="NT-NotationDecl">NotationDecl</nt> | <nt def="NT-PI">PI</nt> | <nt +def="NT-Comment">Comment</nt> </rhs><vc def="vc-PEinMarkupDecl"/><wfc def="wfc-PEinInternalSubset"/> +</prod> +</prodgroup></scrap> +<p diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E82">[E82]</loc>Note +that it is possible to construct a well-formed document containing a <nt def="NT-doctypedecl">doctypedecl</nt> +that neither points to an external subset nor contains an internal subset.</p> +<p>The markup declarations may be made up in whole or in part of the <termref +def="dt-repltext">replacement text</termref> of <termref def="dt-PE">parameter +entities</termref>. The productions later in this specification for individual +nonterminals (<nt def="NT-elementdecl">elementdecl</nt>, <nt def="NT-AttlistDecl">AttlistDecl</nt>, +and so on) describe the declarations <emph>after</emph> all the parameter +entities have been <termref def="dt-include">included</termref>.</p> +<p diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E75">[E75]</loc>Parameter +entity references are recognized anywhere in the DTD (internal and external +subsets and external parameter entities), except in literals, processing instructions, +comments, and the contents of ignored conditional sections (see <specref ref="sec-condition-sect"/>). +They are also recognized in entity value literals. The use of parameter entities +in the internal subset is restricted as described below.</p> +<vcnote id="vc-roottype"><head>Root Element Type</head><p>The <nt def="NT-Name">Name</nt> +in the document type declaration must match the element type of the <termref +def="dt-root">root element</termref>.</p> +</vcnote> +<vcnote id="vc-PEinMarkupDecl"><head>Proper Declaration/PE Nesting</head> +<p>Parameter-entity <termref def="dt-repltext">replacement text</termref> +must be properly nested with markup declarations. That is to say, if either +the first character or the last character of a markup declaration (<nt def="NT-markupdecl">markupdecl</nt> +above) is contained in the replacement text for a <termref def="dt-PERef">parameter-entity +reference</termref>, both must be contained in the same replacement text.</p> +</vcnote> +<wfcnote id="wfc-PEinInternalSubset"><head>PEs in Internal Subset</head><p>In +the internal DTD subset, <termref def="dt-PERef">parameter-entity references</termref> +can occur only where markup declarations can occur, not within markup declarations. +(This does not apply to references that occur in external parameter entities +or to the external subset.)</p> +</wfcnote> +<wfcnote id="ExtSubset" diff="add"><head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc>External +Subset</head><p>The external subset, if any, must match the production for <nt +def="NT-extSubset">extSubset</nt>.</p> +</wfcnote> +<wfcnote id="PE-between-Decls" diff="add"><head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc>PE +Between Declarations</head><p>The replacement text of a parameter entity reference +in a <nt def="NT-DeclSep">DeclSep</nt> must match the production <nt def="NT-extSubsetDecl">extSubsetDecl</nt>.</p> +</wfcnote> +<p>Like the internal subset, the external subset and any external parameter +entities <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc>referenced +in a <nt def="NT-DeclSep">DeclSep</nt></phrase> must consist of a series of +complete markup declarations of the types allowed by the non-terminal symbol <nt +def="NT-markupdecl">markupdecl</nt>, interspersed with white space or <termref +def="dt-PERef">parameter-entity references</termref>. However, portions of +the contents of the external subset or of <phrase diff="add"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc>these </phrase> +external parameter entities may conditionally be ignored by using the <termref +def="dt-cond-section">conditional section</termref> construct; this is not +allowed in the internal subset.</p> +<scrap id="ext-Subset"> +<head>External Subset</head> +<prodgroup pcw2="6" pcw4="17.5" pcw5="9"> +<prod id="NT-extSubset"> +<lhs>extSubset</lhs><rhs><nt def="NT-TextDecl">TextDecl</nt>? <nt def="NT-extSubsetDecl">extSubsetDecl</nt></rhs> +</prod> +<prod id="NT-extSubsetDecl" diff="chg"> +<lhs>extSubsetDecl</lhs><rhs>( <nt def="NT-markupdecl">markupdecl</nt> | <nt +def="NT-conditionalSect">conditionalSect</nt> | <nt diff="chg" def="NT-DeclSep">DeclSep</nt>)*</rhs> +<com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc></com> +</prod> +</prodgroup></scrap> +<p>The external subset and external parameter entities also differ from the +internal subset in that in them, <termref def="dt-PERef">parameter-entity +references</termref> are permitted <emph>within</emph> markup declarations, +not only <emph>between</emph> markup declarations.</p> +<p>An example of an XML document with a document type declaration:</p> +<eg><![CDATA[<?xml version="1.0"?> <!DOCTYPE greeting SYSTEM "hello.dtd"> <greeting>Hello, world!</greeting> ]]></eg> +<p>The <termref def="dt-sysid">system identifier</termref> <quote><code>hello.dtd</code></quote> +gives the <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E78">[E78]</loc>address +(a URI reference)</phrase> of a DTD for the document.</p> +<p>The declarations can also be given locally, as in this example:</p> +<eg><![CDATA[<?xml version="1.0" encoding="UTF-8" ?> +<!DOCTYPE greeting [ + <!ELEMENT greeting (#PCDATA)> +]> +<greeting>Hello, world!</greeting>]]></eg> +<p>If both the external and internal subsets are used, the internal subset +is considered to occur before the external subset. <!-- 'is considered to'? boo. whazzat mean? --> +This has the effect that entity and attribute-list declarations in the internal +subset take precedence over those in the external subset.</p> +</div2> +<div2 id="sec-rmd"> +<head>Standalone Document Declaration</head> +<p>Markup declarations can affect the content of the document, as passed from +an <termref def="dt-xml-proc">XML processor</termref> to an application; examples +are attribute defaults and entity declarations. The standalone document declaration, +which may appear as a component of the XML declaration, signals whether or +not there are such declarations which appear external to the <termref def="dt-docent">document +entity</termref><phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E64">[E64]</loc> +or in parameter entities. <termdef id="dt-extmkpdecl" term="External Markup Declaration">An <term>external +markup declaration</term> is defined as a markup declaration occurring in +the external subset or in a parameter entity (external or internal, the latter +being included because non-validating processors are not required to read +them).</termdef></phrase></p> +<scrap id="fulldtd" lang="ebnf"> +<head>Standalone Document Declaration</head> +<prodgroup pcw2="4" pcw4="19.5" pcw5="9"> +<prod id="NT-SDDecl"> +<lhs>SDDecl</lhs><rhs> <nt def="NT-S">S</nt> 'standalone' <nt def="NT-Eq">Eq</nt> +(("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"')) </rhs><vc def="vc-check-rmd"/> +</prod> +</prodgroup></scrap> +<p>In a standalone document declaration, the value <attval>yes</attval> indicates +that there are no <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E64">[E64]</loc><termref +def="dt-extmkpdecl">external markup declarations</termref></phrase> which +affect the information passed from the XML processor to the application. The +value <attval>no</attval> indicates that there are or may be such external +markup declarations. Note that the standalone document declaration only denotes +the presence of external <emph>declarations</emph>; the presence, in a document, +of references to external <emph>entities</emph>, when those entities are internally +declared, does not change its standalone status.</p> +<p>If there are no external markup declarations, the standalone document declaration +has no meaning. If there are external markup declarations but there is no +standalone document declaration, the value <attval>no</attval> is assumed.</p> +<p>Any XML document for which <code>standalone="no"</code> holds can be converted +algorithmically to a standalone document, which may be desirable for some +network delivery applications.</p> +<vcnote id="vc-check-rmd"><head>Standalone Document Declaration</head><p>The +standalone document declaration must have the value <attval>no</attval> if +any external markup declarations contain declarations of:</p> +<ulist> +<item><p>attributes with <termref def="dt-default">default</termref> values, +if elements to which these attributes apply appear in the document without +specifications of values for these attributes, or</p></item> +<item><p>entities (other than &magicents;), if <termref def="dt-entref">references</termref> +to those entities appear in the document, or</p></item> +<item><p>attributes with values subject to <titleref href="#AVNormalize">normalization</titleref>, +where the attribute appears in the document with a value which will change +as a result of normalization, or</p></item> +<item><p>element types with <termref def="dt-elemcontent">element content</termref>, +if white space occurs directly within any instance of those types.</p></item> +</ulist> +</vcnote> +<p>An example XML declaration with a standalone document declaration:</p> +<eg><?xml version="&versionOfXML;" standalone='yes'?></eg> +</div2> +<div2 id="sec-white-space"> +<head>White Space Handling</head> +<p>In editing XML documents, it is often convenient to use <quote>white space</quote> +(spaces, tabs, and blank lines<phrase diff="del"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E39">[E39]</loc>, +denoted by the nonterminal <nt def="NT-S">S</nt> in this specification</phrase>) +to set apart the markup for greater readability. Such white space is typically +not intended for inclusion in the delivered version of the document. On the +other hand, <quote>significant</quote> white space that should be preserved +in the delivered version is common, for example in poetry and source code.</p> +<p>An <termref def="dt-xml-proc">XML processor</termref> must always pass +all characters in a document that are not markup through to the application. +A <termref def="dt-validating"> validating XML processor</termref> must also +inform the application which of these characters constitute white space appearing +in <termref def="dt-elemcontent">element content</termref>.</p> +<p>A special <termref def="dt-attr">attribute</termref> named <att>xml:space</att> +may be attached to an element to signal an intention that in that element, +white space should be preserved by applications. In valid documents, this +attribute, like any other, must be <termref def="dt-attdecl">declared</termref> +if it is used. When declared, it must be given as an <termref def="dt-enumerated">enumerated +type</termref> whose <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E81">[E81]</loc>values +are one or both of</phrase> <attval>default</attval> and <attval>preserve</attval>. +For example:</p> +<eg diff="chg"><![CDATA[<!ATTLIST poem xml:space (default|preserve) 'preserve'>]]> + +<!-- <loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E81">[E81]</loc>--> +<!ATTLIST pre xml:space (preserve) #FIXED 'preserve'></eg> +<p>The value <attval>default</attval> signals that applications' default white-space +processing modes are acceptable for this element; the value <attval>preserve</attval> +indicates the intent that applications preserve all the white space. This +declared intent is considered to apply to all elements within the content +of the element where it is specified, unless overriden with another instance +of the <att>xml:space</att> attribute.</p> +<p>The <termref def="dt-root">root element</termref> of any document is considered +to have signaled no intentions as regards application space handling, unless +it provides a value for this attribute or the attribute is declared with a +default value.</p> +</div2> +<div2 id="sec-line-ends"> +<head>End-of-Line Handling</head> +<p>XML <termref def="dt-parsedent">parsed entities</termref> are often stored +in computer files which, for editing convenience, are organized into lines. +These lines are typically separated by some combination of the characters +carriage-return (#xD) and line-feed (#xA).</p> +<p diff="del">To simplify the tasks of <termref def="dt-app">applications</termref>, +wherever an external parsed entity or the literal entity value of an internal +parsed entity contains either the literal two-character sequence <quote>#xD#xA</quote> +or a standalone literal #xD, an <termref def="dt-xml-proc">XML processor</termref> +must pass to the application the single character #xA. (This behavior can +conveniently be produced by normalizing all line breaks to #xA on input, before +parsing.)</p> +<p diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E104">[E104]</loc>To +simplify the tasks of <termref def="dt-app">applications</termref>, the characters +passed to an application by the <termref def="dt-xml-proc">XML processor</termref> +must be as if the XML processor normalized all line breaks in external parsed +entities (including the document entity) on input, before parsing, by translating +both the two-character sequence #xD #xA and any #xD that is not followed by +#xA to a single #xA character.</p> +</div2> +<div2 id="sec-lang-tag"> +<head>Language Identification</head> +<p>In document processing, it is often useful to identify the natural or formal +language in which the content is written. A special <termref def="dt-attr">attribute</termref> +named <att>xml:lang</att> may be inserted in documents to specify the language +used in the contents and attribute values of any element in an XML document. +In valid documents, this attribute, like any other, must be <termref def="dt-attdecl">declared</termref> +if it is used. <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E73">[E73]</loc>The +values of the attribute are language identifiers as defined by <bibref ref="RFC1766"/>, <titleref>Tags +for the Identification of Languages</titleref>, or its successor on the IETF +Standards Track.</phrase></p> +<note diff="add"> +<p><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E73">[E73]</loc><bibref +ref="RFC1766"/> tags are constructed from two-letter language codes as defined +by <bibref ref="ISO639"/>, from two-letter country codes as defined by <bibref +ref="ISO3166"/>, or from language identifiers registered with the Internet +Assigned Numbers Authority <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</loc><bibref +diff="chg" ref="IANA-LANGCODES"/></phrase>. It is expected that the successor +to <bibref ref="RFC1766"/> will introduce three-letter language codes for +languages not presently covered by <bibref ref="ISO639"/>.</p> +</note> +<p diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E73">[E73]</loc>(Productions +33 through 38 have been removed.)</p> +<scrap diff="del" lang="ebnf"> +<head>Language Identification</head> +<prod id="NT-LanguageID"> +<lhs>LanguageID</lhs><rhs><nt def="NT-Langcode">Langcode</nt> ('-' <nt def="NT-Subcode">Subcode</nt>)*</rhs> +</prod> +<prod id="NT-Langcode"> +<lhs>Langcode</lhs><rhs><nt def="NT-ISO639Code">ISO639Code</nt> | <nt def="NT-IanaCode">IanaCode</nt> +| <nt def="NT-UserCode">UserCode</nt></rhs> +</prod> +<prod id="NT-ISO639Code"> +<lhs>ISO639Code</lhs><rhs>([a-z] | [A-Z]) ([a-z] | [A-Z])</rhs> +</prod> +<prod id="NT-IanaCode"> +<lhs>IanaCode</lhs><rhs>('i' | 'I') '-' ([a-z] | [A-Z])+</rhs> +</prod> +<prod id="NT-UserCode"> +<lhs>UserCode</lhs><rhs>('x' | 'X') '-' ([a-z] | [A-Z])+</rhs> +</prod> +<prod id="NT-Subcode"> +<lhs>Subcode</lhs><rhs>([a-z] | [A-Z])+</rhs> +</prod> +</scrap> +<p diff="del">The <nt def="NT-Langcode">Langcode</nt> may be any of the following:</p> +<ulist diff="del"> +<item><p>a two-letter language code as defined by <bibref ref="ISO639"/>, <titleref>Codes +for the representation of names of languages</titleref></p></item> +<item><p>a language identifier registered with the Internet Assigned Numbers +Authority <bibref diff="chg" ref="IANA-LANGCODES"/>; these begin with the +prefix <quote><code>i-</code></quote> (or <quote><code>I-</code></quote>)</p> +</item> +<item><p>a language identifier assigned by the user, or agreed on between +parties in private use; these must begin with the prefix <quote><code>x-</code></quote> +or <quote><code>X-</code></quote> in order to ensure that they do not conflict +with names later standardized or registered with IANA</p></item> +</ulist> +<p diff="del">There may be any number of <nt def="NT-Subcode">Subcode</nt> +segments; if the first subcode segment exists and the Subcode consists of +two letters, then it must be a country code from <bibref ref="ISO3166"/>, +"Codes for the representation of names of countries." If the first subcode +consists of more than two letters, it must be a subcode for the language in +question registered with IANA, unless the <nt def="NT-Langcode">Langcode</nt> +begins with the prefix "<code>x-</code>" or "<code>X-</code>". </p> +<p diff="del">It is customary to give the language code in lower case, and +the country code (if any) in upper case. Note that these values, unlike other +names in XML documents, are case insensitive.</p> +<p>For example:</p> +<eg><![CDATA[<p xml:lang="en">The quick brown fox jumps over the lazy dog.</p> +<p xml:lang="en-GB">What colour is it?</p> +<p xml:lang="en-US">What color is it?</p> +<sp who="Faust" desc='leise' xml:lang="de"> + <l>Habe nun, ach! Philosophie,</l> + <l>Juristerei, und Medizin</l> + <l>und leider auch Theologie</l> + <l>durchaus studiert mit heißem Bemüh'n.</l> +</sp>]]></eg> +<!--<p>The xml:lang value is considered to apply both to the contents of an +element and +(unless otherwise via attribute default values) to the +values of all of its attributes with free-text (CDATA) values. --> +<p>The intent declared with <att>xml:lang</att> is considered to apply to +all attributes and content of the element where it is specified, unless overridden +with an instance of <att>xml:lang</att> on another element within that content.</p> +<!-- +If no +value is specified for xml:lang on an element, and no default value is +defined for it in the DTD, then the xml:lang attribute of any element +takes the same value it has in the parent element, if any. The two +technical terms in the following example both have the same effective +value for xml:lang: + + <p xml:lang="en">Here the keywords are + <term xml:lang="en">shift</term> and + <term>reduce</term>. ...</p> + +The application, not the XML processor, is responsible for this ' +inheritance' of attribute values. +--> +<p>A simple declaration for <att>xml:lang</att> might take the form</p> +<eg>xml:lang NMTOKEN #IMPLIED</eg> +<p>but specific default values may also be given, if appropriate. In a collection +of French poems for English students, with glosses and notes in English, the <att>xml:lang</att> +attribute might be declared this way:</p> +<eg><![CDATA[<!ATTLIST poem xml:lang NMTOKEN 'fr'> +<!ATTLIST gloss xml:lang NMTOKEN 'en'> +<!ATTLIST note xml:lang NMTOKEN 'en'>]]></eg> +</div2> +</div1> +<!-- &Elements; --> +<div1 id="sec-logical-struct"> +<head>Logical Structures</head> +<p><termdef id="dt-element" term="Element">Each <termref def="dt-xml-doc">XML +document</termref> contains one or more <term>elements</term>, the boundaries +of which are either delimited by <termref def="dt-stag">start-tags</termref> +and <termref def="dt-etag">end-tags</termref>, or, for <termref def="dt-empty">empty</termref> +elements, by an <termref def="dt-eetag">empty-element tag</termref>. Each +element has a type, identified by name, sometimes called its <quote>generic +identifier</quote> (GI), and may have a set of attribute specifications.</termdef> +Each attribute specification has a <termref def="dt-attrname">name</termref> +and a <termref def="dt-attrval">value</termref>.</p> +<scrap lang="ebnf"> +<head>Element</head> +<prod id="NT-element"> +<lhs>element</lhs><rhs><nt def="NT-EmptyElemTag">EmptyElemTag</nt></rhs> +<rhs>| <nt def="NT-STag">STag</nt> <nt def="NT-content">content</nt> <nt def="NT-ETag">ETag</nt></rhs> +<wfc def="GIMatch"/><vc def="elementvalid"/> +</prod> +</scrap> +<p>This specification does not constrain the semantics, use, or (beyond syntax) +names of the element types and attributes, except that names beginning with +a match to <code>(('X'|'x')('M'|'m')('L'|'l'))</code> are reserved for standardization +in this or future versions of this specification.</p> +<wfcnote id="GIMatch"><head>Element Type Match</head><p>The <nt def="NT-Name">Name</nt> +in an element's end-tag must match the element type in the start-tag.</p> +</wfcnote> +<vcnote id="elementvalid"><head>Element Valid</head><p>An element is valid +if there is a declaration matching <nt def="NT-elementdecl">elementdecl</nt> +where the <nt def="NT-Name">Name</nt> matches the element type, and one of +the following holds:</p> +<olist> +<item><p>The declaration matches <kw>EMPTY</kw> and the element has no <termref +def="dt-content">content</termref>.</p></item> +<item><p>The declaration matches <nt def="NT-children">children</nt> and the +sequence of <termref def="dt-parentchild">child elements</termref> belongs +to the language generated by the regular expression in the content model, +with optional white space (characters matching the nonterminal <nt def="NT-S">S</nt>) +between <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E59">[E59]</loc>the +start-tag and the first child element, between child elements, or between +the last child element and the end-tag. Note that a CDATA section containing +only white space does not match the nonterminal <nt def="NT-S">S</nt>, and +hence cannot appear in these positions.</phrase></p></item> +<item><p>The declaration matches <nt def="NT-Mixed">Mixed</nt> and the content +consists of <termref def="dt-chardata">character data</termref> and <termref +def="dt-parentchild">child elements</termref> whose types match names in the +content model.</p></item> +<item><p>The declaration matches <kw>ANY</kw>, and the types of any <termref +def="dt-parentchild">child elements</termref> have been declared.</p></item> +</olist> +</vcnote> +<div2 id="sec-starttags"> +<head>Start-Tags, End-Tags, and Empty-Element Tags</head> +<p><termdef id="dt-stag" term="Start-Tag">The beginning of every non-empty +XML element is marked by a <term>start-tag</term>.</termdef></p> +<scrap lang="ebnf"> +<head>Start-tag</head> +<prodgroup pcw2="6" pcw4="15" pcw5="11.5"> +<prod id="NT-STag"> +<lhs>STag</lhs><rhs>'<' <nt def="NT-Name">Name</nt> (<nt def="NT-S">S</nt> <nt +def="NT-Attribute">Attribute</nt>)* <nt def="NT-S">S</nt>? '>'</rhs><wfc def="uniqattspec"/> +</prod> +<prod id="NT-Attribute"> +<lhs>Attribute</lhs><rhs><nt def="NT-Name">Name</nt> <nt def="NT-Eq">Eq</nt> <nt +def="NT-AttValue">AttValue</nt></rhs><vc def="ValueType"/><wfc def="NoExternalRefs"/> +<wfc def="CleanAttrVals"/> +</prod> +</prodgroup></scrap> +<p>The <nt def="NT-Name">Name</nt> in the start- and end-tags gives the element's <term>type</term>. <termdef +id="dt-attr" term="Attribute"> The <nt def="NT-Name">Name</nt>-<nt def="NT-AttValue">AttValue</nt> +pairs are referred to as the <term>attribute specifications</term> of the +element</termdef>, <termdef id="dt-attrname" term="Attribute Name">with the <nt +def="NT-Name">Name</nt> in each pair referred to as the <term>attribute name</term></termdef> +and <termdef id="dt-attrval" term="Attribute Value">the content of the <nt +def="NT-AttValue">AttValue</nt> (the text between the <code>'</code> or <code>"</code> +delimiters) as the <term>attribute value</term>.</termdef><phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E46">[E46]</loc>Note +that the order of attribute specifications in a start-tag or empty-element +tag is not significant.</phrase></p> +<wfcnote id="uniqattspec"><head>Unique Att Spec</head><p>No attribute name +may appear more than once in the same start-tag or empty-element tag.</p> +</wfcnote> +<vcnote id="ValueType"><head>Attribute Value Type</head><p>The attribute must +have been declared; the value must be of the type declared for it. (For attribute +types, see <specref ref="attdecls"/>.)</p> +</vcnote> +<wfcnote id="NoExternalRefs"><head>No External Entity References</head><p>Attribute +values cannot contain direct or indirect entity references to external entities.</p> +</wfcnote> +<wfcnote id="CleanAttrVals"><head>No <code><</code> in Attribute Values</head> +<p>The <termref def="dt-repltext">replacement text</termref> of any entity +referred to directly or indirectly in an attribute value <phrase diff="del"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E83">[E83]</loc>(other +than <quote><code>&lt;</code></quote>) </phrase>must not contain a <code><</code>.</p> +</wfcnote> +<p>An example of a start-tag:</p> +<eg><termdef id="dt-dog" term="dog"></eg> +<p><termdef id="dt-etag" term="End Tag">The end of every element that begins +with a start-tag must be marked by an <term>end-tag</term> containing a name +that echoes the element's type as given in the start-tag:</termdef></p> +<scrap lang="ebnf"> +<head>End-tag</head> +<prodgroup pcw2="6" pcw4="15" pcw5="11.5"> +<prod id="NT-ETag"> +<lhs>ETag</lhs><rhs>'</' <nt def="NT-Name">Name</nt> <nt def="NT-S">S</nt>? +'>'</rhs> +</prod> +</prodgroup></scrap> +<p>An example of an end-tag:</p> +<eg></termdef></eg> +<p><termdef id="dt-content" term="Content">The <termref def="dt-text">text</termref> +between the start-tag and end-tag is called the element's <term>content</term>:</termdef></p> +<scrap lang="ebnf"> +<head>Content of Elements</head> +<prodgroup pcw2="6" pcw4="15" pcw5="11.5"> +<prod id="NT-content" diff="chg"> +<lhs>content</lhs><rhs><nt def="NT-CharData">CharData</nt>? ((<nt def="NT-element">element</nt> +| <nt def="NT-Reference">Reference</nt> | <nt def="NT-CDSect">CDSect</nt> +| <nt def="NT-PI">PI</nt> | <nt def="NT-Comment">Comment</nt>) <nt def="NT-CharData">CharData</nt>?)*</rhs> +<com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E71">[E71]</loc></com> +</prod> +</prodgroup></scrap> +<p><phrase diff="chg"><termdef id="dt-empty" term="Empty"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E97">[E97]</loc>An element +with no content is said to be <term>empty</term>.</termdef> The representation +of an empty element is either a start-tag immediately followed by an end-tag, +or an empty-element tag.</phrase> <termdef id="dt-eetag" term="empty-element tag">An <term>empty-element +tag</term> takes a special form:</termdef></p> +<scrap lang="ebnf"> +<head>Tags for Empty Elements</head> +<prodgroup pcw2="6" pcw4="15" pcw5="11.5"> +<prod id="NT-EmptyElemTag"> +<lhs>EmptyElemTag</lhs><rhs>'<' <nt def="NT-Name">Name</nt> (<nt def="NT-S">S</nt> <nt +def="NT-Attribute">Attribute</nt>)* <nt def="NT-S">S</nt>? '/>'</rhs><wfc +def="uniqattspec"/> +</prod> +</prodgroup></scrap> +<p>Empty-element tags may be used for any element which has no content, whether +or not it is declared using the keyword <kw>EMPTY</kw>. <termref def="dt-interop">For +interoperability</termref>, the empty-element tag <phrase diff="chg"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E45">[E45]</loc>should +be used, and should only be used,</phrase> for elements which are declared +EMPTY.</p> +<p>Examples of empty elements:</p> +<eg><IMG align="left" + src="http://www.w3.org/Icons/WWW/w3c_home" /> +<br></br> +<br/></eg> +</div2> +<div2 id="elemdecls"> +<head>Element Type Declarations</head> +<p>The <termref def="dt-element">element</termref> structure of an <termref +def="dt-xml-doc">XML document</termref> may, for <termref def="dt-valid">validation</termref> +purposes, be constrained using element type and attribute-list declarations. +An element type declaration constrains the element's <termref def="dt-content">content</termref>.</p> +<p>Element type declarations often constrain which element types can appear +as <termref def="dt-parentchild">children</termref> of the element. At user +option, an XML processor may issue a warning when a declaration mentions an +element type for which no declaration is provided, but this is not an error.</p> +<p><termdef id="dt-eldecl" term="Element Type declaration">An <term>element +type declaration</term> takes the form:</termdef></p> +<scrap lang="ebnf"> +<head>Element Type Declaration</head> +<prodgroup pcw2="5.5" pcw4="18" pcw5="9"> +<prod id="NT-elementdecl"> +<lhs>elementdecl</lhs><rhs>'<!ELEMENT' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt> <nt +def="NT-S">S</nt> <nt def="NT-contentspec">contentspec</nt> <nt def="NT-S">S</nt>? +'>'</rhs><vc def="EDUnique"/> +</prod> +<prod id="NT-contentspec"> +<lhs>contentspec</lhs><rhs>'EMPTY' | 'ANY' | <nt def="NT-Mixed">Mixed</nt> +| <nt def="NT-children">children</nt> </rhs> +</prod> +</prodgroup></scrap> +<p>where the <nt def="NT-Name">Name</nt> gives the element type being declared.</p> +<vcnote id="EDUnique"><head>Unique Element Type Declaration</head><p>No element +type may be declared more than once.</p> +</vcnote> +<p>Examples of element type declarations:</p> +<eg><!ELEMENT br EMPTY> +<!ELEMENT p (#PCDATA|emph)* > +<!ELEMENT %name.para; %content.para; > +<!ELEMENT container ANY></eg> +<div3 id="sec-element-content"> +<head>Element Content</head> +<p><termdef id="dt-elemcontent" term="Element content">An element <termref +def="dt-stag">type</termref> has <term>element content</term> when elements +of that type must contain only <termref def="dt-parentchild">child</termref> +elements (no character data), optionally separated by white space (characters +matching the nonterminal <nt def="NT-S">S</nt>).</termdef><termdef id="dt-content-model" +term="Content model">In this case, the constraint includes a <phrase diff="chg"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E55">[E55]</loc><term>content +model</term></phrase>, a simple grammar governing the allowed types of the +child elements and the order in which they are allowed to appear.</termdef> +The grammar is built on content particles (<nt def="NT-cp">cp</nt>s), which +consist of names, choice lists of content particles, or sequence lists of +content particles:</p> +<scrap lang="ebnf"> +<head>Element-content Models</head> +<prodgroup pcw2="5.5" pcw4="16" pcw5="11"> +<prod id="NT-children"> +<lhs>children</lhs><rhs>(<nt def="NT-choice">choice</nt> | <nt def="NT-seq">seq</nt>) +('?' | '*' | '+')?</rhs> +</prod> +<prod id="NT-cp"> +<lhs>cp</lhs><rhs>(<nt def="NT-Name">Name</nt> | <nt def="NT-choice">choice</nt> +| <nt def="NT-seq">seq</nt>) ('?' | '*' | '+')?</rhs> +</prod> +<prod id="NT-choice" diff="chg"> +<lhs>choice</lhs><rhs>'(' <nt def="NT-S">S</nt>? <nt def="NT-cp">cp</nt> ( <nt +def="NT-S">S</nt>? '|' <nt def="NT-S">S</nt>? <nt def="NT-cp">cp</nt> )+ <nt +def="NT-S">S</nt>? ')'</rhs><com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E50">[E50]</loc></com> +<com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E52">[E52]</loc></com> +<vc def="vc-PEinGroup"/> +</prod> +<prod id="NT-seq" diff="chg"> +<lhs>seq</lhs><rhs>'(' <nt def="NT-S">S</nt>? <nt def="NT-cp">cp</nt> ( <nt +def="NT-S">S</nt>? ',' <nt def="NT-S">S</nt>? <nt def="NT-cp">cp</nt> )* <nt +def="NT-S">S</nt>? ')'</rhs><com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E52">[E52]</loc></com> +<vc def="vc-PEinGroup"/> +</prod> +</prodgroup></scrap> +<p>where each <nt def="NT-Name">Name</nt> is the type of an element which +may appear as a <termref def="dt-parentchild">child</termref>. Any content +particle in a choice list may appear in the <termref def="dt-elemcontent">element +content</termref> at the location where the choice list appears in the grammar; +content particles occurring in a sequence list must each appear in the <termref +def="dt-elemcontent">element content</termref> in the order given in the list. +The optional character following a name or list governs whether the element +or the content particles in the list may occur one or more (<code>+</code>), +zero or more (<code>*</code>), or zero or one times (<code>?</code>). The +absence of such an operator means that the element or content particle must +appear exactly once. This syntax and meaning are identical to those used in +the productions in this specification.</p> +<p>The content of an element matches a content model if and only if it is +possible to trace out a path through the content model, obeying the sequence, +choice, and repetition operators and matching each element in the content +against an element type in the content model. <termref def="dt-compat">For +compatibility</termref>, it is an error if an element in the document can +match more than one occurrence of an element type in the content model. For +more information, see <specref ref="determinism"/>.</p> +<!--appendix <specref ref="determinism"/>.--> +<!-- appendix on deterministic content models. --> +<vcnote id="vc-PEinGroup"><head>Proper Group/PE Nesting</head><p>Parameter-entity <termref +def="dt-repltext">replacement text</termref> must be properly nested with <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E11">[E11]</loc>parenthesized</phrase> +groups. That is to say, if either of the opening or closing parentheses in +a <nt def="NT-choice">choice</nt>, <nt def="NT-seq">seq</nt>, or <nt def="NT-Mixed">Mixed</nt> +construct is contained in the replacement text for a <termref def="dt-PERef">parameter +entity</termref>, both must be contained in the same replacement text.</p> +<p diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E19">[E19]</loc><termref +def="dt-interop">For interoperability</termref>, if a parameter-entity reference +appears in a <nt def="NT-choice">choice</nt>, <nt def="NT-seq">seq</nt>, or <nt +def="NT-Mixed">Mixed</nt> construct, its replacement text should contain at +least one non-blank character, and neither the first nor last non-blank character +of the replacement text should be a connector (<code>|</code> or <code>,</code>).</p> +</vcnote> +<p>Examples of element-content models:</p> +<eg><!ELEMENT spec (front, body, back?)> +<!ELEMENT div1 (head, (p | list | note)*, div2*)> +<!ELEMENT dictionary-body (%div.mix; | %dict.mix;)*></eg> +</div3> +<div3 id="sec-mixed-content"> +<head>Mixed Content</head> +<p><termdef id="dt-mixed" term="Mixed Content">An element <termref def="dt-stag">type</termref> +has <term>mixed content</term> when elements of that type may contain character +data, optionally interspersed with <termref def="dt-parentchild">child</termref> +elements.</termdef> In this case, the types of the child elements may be constrained, +but not their order or their number of occurrences:</p> +<scrap lang="ebnf"> +<head>Mixed-content Declaration</head> +<prodgroup pcw2="5.5" pcw4="16" pcw5="11"> +<prod id="NT-Mixed"> +<lhs>Mixed</lhs><rhs>'(' <nt def="NT-S">S</nt>? '#PCDATA' (<nt def="NT-S">S</nt>? +'|' <nt def="NT-S">S</nt>? <nt def="NT-Name">Name</nt>)* <nt def="NT-S">S</nt>? +')*' </rhs> +<rhs>| '(' <nt def="NT-S">S</nt>? '#PCDATA' <nt def="NT-S">S</nt>? ')' </rhs> +<vc def="vc-PEinGroup"/><vc def="vc-MixedChildrenUnique"/> +</prod> +</prodgroup></scrap> +<p>where the <nt def="NT-Name">Name</nt>s give the types of elements that +may appear as children. <phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E10">[E10]</loc>The +keyword <kw>#PCDATA</kw> derives historically from the term <quote>parsed +character data.</quote></phrase></p> +<vcnote id="vc-MixedChildrenUnique"><head>No Duplicate Types</head><p>The +same name must not appear more than once in a single mixed-content declaration.</p> +</vcnote> +<p>Examples of mixed content declarations:</p> +<eg><!ELEMENT p (#PCDATA|a|ul|b|i|em)*> +<!ELEMENT p (#PCDATA | %font; | %phrase; | %special; | %form;)* > +<!ELEMENT b (#PCDATA)></eg> +</div3> +</div2> +<div2 id="attdecls"> +<head>Attribute-List Declarations</head> +<p><termref def="dt-attr">Attributes</termref> are used to associate name-value +pairs with <termref def="dt-element">elements</termref>. Attribute specifications +may appear only within <termref def="dt-stag">start-tags</termref> and <termref +def="dt-eetag">empty-element tags</termref>; thus, the productions used to +recognize them appear in <specref ref="sec-starttags"/>. Attribute-list declarations +may be used:</p> +<ulist> +<item><p>To define the set of attributes pertaining to a given element type.</p> +</item> +<item><p>To establish type constraints for these attributes.</p></item> +<item><p>To provide <termref def="dt-default">default values</termref> for +attributes.</p></item> +</ulist> +<p><termdef id="dt-attdecl" term="Attribute-List Declaration"> <term>Attribute-list +declarations</term> specify the name, data type, and default value (if any) +of each attribute associated with a given element type:</termdef></p> +<scrap lang="ebnf"> +<head>Attribute-list Declaration</head> +<prod id="NT-AttlistDecl"> +<lhs>AttlistDecl</lhs><rhs>'<!ATTLIST' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt> <nt +def="NT-AttDef">AttDef</nt>* <nt def="NT-S">S</nt>? '>'</rhs> +</prod> +<prod id="NT-AttDef"> +<lhs>AttDef</lhs><rhs><nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt> <nt +def="NT-S">S</nt> <nt def="NT-AttType">AttType</nt> <nt def="NT-S">S</nt> <nt +def="NT-DefaultDecl">DefaultDecl</nt></rhs> +</prod> +</scrap> +<p>The <nt def="NT-Name">Name</nt> in the <nt def="NT-AttlistDecl">AttlistDecl</nt> +rule is the type of an element. At user option, an XML processor may issue +a warning if attributes are declared for an element type not itself declared, +but this is not an error. The <nt def="NT-Name">Name</nt> in the <nt def="NT-AttDef">AttDef</nt> +rule is the name of the attribute.</p> +<p>When more than one <nt def="NT-AttlistDecl">AttlistDecl</nt> is provided +for a given element type, the contents of all those provided are merged. When +more than one definition is provided for the same attribute of a given element +type, the first declaration is binding and later declarations are ignored. <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E9">[E9]</loc><termref +def="dt-interop">For interoperability,</termref> writers of DTDs may choose +to provide at most one attribute-list declaration for a given element type, +at most one attribute definition for a given attribute name in an attribute-list +declaration, and at least one attribute definition in each attribute-list +declaration.</phrase> For interoperability, an XML processor may at user option +issue a warning when more than one attribute-list declaration is provided +for a given element type, or more than one attribute definition is provided +for a given attribute, but this is not an error.</p> +<div3 id="sec-attribute-types"> +<head>Attribute Types</head> +<p>XML attribute types are of three kinds: a string type, a set of tokenized +types, and enumerated types. The string type may take any literal string as +a value; the tokenized types have varying lexical and semantic constraints<phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E8">[E8]</loc>. +The validity constraints noted in the grammar are applied after the attribute +value has been normalized as described in <specref ref="attdecls"/>.</phrase></p> +<scrap lang="ebnf"> +<head>Attribute Types</head> +<prodgroup pcw4="14" pcw5="11.5"> +<prod id="NT-AttType"> +<lhs>AttType</lhs><rhs><nt def="NT-StringType">StringType</nt> | <nt def="NT-TokenizedType">TokenizedType</nt> +| <nt def="NT-EnumeratedType">EnumeratedType</nt> </rhs> +</prod> +<prod id="NT-StringType"> +<lhs>StringType</lhs><rhs>'CDATA'</rhs> +</prod> +<prod id="NT-TokenizedType"> +<lhs>TokenizedType</lhs><rhs>'ID'</rhs><vc def="id"/><vc def="one-id-per-el"/> +<vc def="id-default"/> +<rhs>| 'IDREF'</rhs><vc def="idref"/> +<rhs>| 'IDREFS'</rhs><vc def="idref"/> +<rhs>| 'ENTITY'</rhs><vc def="entname"/> +<rhs>| 'ENTITIES'</rhs><vc def="entname"/> +<rhs>| 'NMTOKEN'</rhs><vc def="nmtok"/> +<rhs>| 'NMTOKENS'</rhs><vc def="nmtok"/> +</prod> +</prodgroup></scrap> +<vcnote id="id"><head>ID</head><p>Values of type <kw>ID</kw> must match the <nt +def="NT-Name">Name</nt> production. A name must not appear more than once +in an XML document as a value of this type; i.e., ID values must uniquely +identify the elements which bear them.</p> +</vcnote> +<vcnote id="one-id-per-el"><head>One ID per Element Type</head><p>No element +type may have more than one ID attribute specified.</p> +</vcnote> +<vcnote id="id-default"><head>ID Attribute Default</head><p>An ID attribute +must have a declared default of <kw>#IMPLIED</kw> or <kw>#REQUIRED</kw>.</p> +</vcnote> +<vcnote id="idref"><head>IDREF</head><p>Values of type <kw>IDREF</kw> must +match the <nt def="NT-Name">Name</nt> production, and values of type <kw>IDREFS</kw> +must match <nt def="NT-Names">Names</nt>; each <nt def="NT-Name">Name</nt> +must match the value of an ID attribute on some element in the XML document; +i.e. <kw>IDREF</kw> values must match the value of some ID attribute.</p> +</vcnote> +<vcnote id="entname"><head>Entity Name</head><p>Values of type <kw>ENTITY</kw> +must match the <nt def="NT-Name">Name</nt> production, values of type <kw>ENTITIES</kw> +must match <nt def="NT-Names">Names</nt>; each <nt def="NT-Name">Name</nt> +must match the name of an <termref def="dt-unparsed">unparsed entity</termref> +declared in the <termref def="dt-doctype">DTD</termref>.</p> +</vcnote> +<vcnote id="nmtok"><head>Name Token</head><p>Values of type <kw>NMTOKEN</kw> +must match the <nt def="NT-Nmtoken">Nmtoken</nt> production; values of type <kw>NMTOKENS</kw> +must match <termref def="NT-Nmtokens">Nmtokens</termref>.</p> +</vcnote> +<!-- why? +<p>The XML processor must normalize attribute values before +passing them to the application, as described in +<specref ref="AVNormalize"/>.</p>--> +<p><termdef id="dt-enumerated" term="Enumerated Attribute +Values"><term>Enumerated attributes</term> can take one of a list of values +provided in the declaration</termdef>. There are two kinds of enumerated types:</p> +<scrap lang="ebnf"> +<head>Enumerated Attribute Types</head> +<prod id="NT-EnumeratedType"> +<lhs>EnumeratedType</lhs><rhs><nt def="NT-NotationType">NotationType</nt> +| <nt def="NT-Enumeration">Enumeration</nt> </rhs> +</prod> +<prod id="NT-NotationType"> +<lhs>NotationType</lhs><rhs>'NOTATION' <nt def="NT-S">S</nt> '(' <nt def="NT-S">S</nt>? <nt +def="NT-Name">Name</nt> (<nt def="NT-S">S</nt>? '|' <nt def="NT-S">S</nt>? <nt +def="NT-Name">Name</nt>)* <nt def="NT-S">S</nt>? ')' </rhs><vc def="notatn"/> +<vc def="OneNotationPer" diff="add"/><vc def="NoNotationEmpty" diff="add"/> +</prod> +<prod id="NT-Enumeration"> +<lhs>Enumeration</lhs><rhs>'(' <nt def="NT-S">S</nt>? <nt def="NT-Nmtoken">Nmtoken</nt> +(<nt def="NT-S">S</nt>? '|' <nt def="NT-S">S</nt>? <nt def="NT-Nmtoken">Nmtoken</nt>)* <nt +def="NT-S">S</nt>? ')'</rhs><vc def="enum"/> +</prod> +</scrap> +<p>A <kw>NOTATION</kw> attribute identifies a <termref def="dt-notation">notation</termref>, +declared in the DTD with associated system and/or public identifiers, to be +used in interpreting the element to which the attribute is attached.</p> +<vcnote id="notatn"><head>Notation Attributes</head><p>Values of this type +must match one of the <titleref href="#Notations">notation</titleref> names +included in the declaration; all notation names in the declaration must be +declared.</p> +</vcnote> +<vcnote id="OneNotationPer" diff="add"><head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E7">[E7]</loc>One +Notation Per Element Type</head><p>No element type may have more than one <kw>NOTATION</kw> +attribute specified.</p> +</vcnote> +<vcnote id="NoNotationEmpty" diff="add"><head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E68">[E68]</loc>No +Notation on Empty Element</head><p><termref def="dt-compat">For compatibility</termref>, +an attribute of type <kw>NOTATION</kw> must not be declared on an element +declared <kw>EMPTY</kw>.</p> +</vcnote> +<vcnote id="enum"><head>Enumeration</head><p>Values of this type must match +one of the <nt def="NT-Nmtoken">Nmtoken</nt> tokens in the declaration.</p> +</vcnote> +<p><termref def="dt-interop">For interoperability,</termref> the same <nt +def="NT-Nmtoken">Nmtoken</nt> should not occur more than once in the enumerated +attribute types of a single element type.</p> +</div3> +<div3 id="sec-attr-defaults"> +<head>Attribute Defaults</head> +<p>An <termref def="dt-attdecl">attribute declaration</termref> provides information +on whether the attribute's presence is required, and if not, how an XML processor +should react if a declared attribute is absent in a document.</p> +<scrap lang="ebnf"> +<head>Attribute Defaults</head> +<prodgroup pcw4="14" pcw5="11.5"> +<prod id="NT-DefaultDecl"> +<lhs>DefaultDecl</lhs><rhs>'#REQUIRED' | '#IMPLIED' </rhs> +<rhs>| (('#FIXED' S)? <nt def="NT-AttValue">AttValue</nt>)</rhs><vc def="RequiredAttr"/> +<vc def="defattrvalid"/><wfc def="CleanAttrVals"/><vc def="FixedAttr"/> +</prod> +</prodgroup></scrap> +<p>In an attribute declaration, <kw>#REQUIRED</kw> means that the attribute +must always be provided, <kw>#IMPLIED</kw> that no default value is provided. <!-- not any more!! +<kw>#IMPLIED</kw> means that if the attribute is omitted +from an element of this type, +the XML processor must inform the application +that no value was specified; no constraint is placed on the behavior +of the application. --> <termdef id="dt-default" term="Attribute Default">If +the declaration is neither <kw>#REQUIRED</kw> nor <kw>#IMPLIED</kw>, then +the <nt def="NT-AttValue">AttValue</nt> value contains the declared <term>default</term> +value; the <kw>#FIXED</kw> keyword states that the attribute must always have +the default value. If a default value is declared, when an XML processor encounters +an omitted attribute, it is to behave as though the attribute were present +with the declared default value.</termdef></p> +<vcnote id="RequiredAttr"><head>Required Attribute</head><p>If the default +declaration is the keyword <kw>#REQUIRED</kw>, then the attribute must be +specified for all elements of the type in the attribute-list declaration.</p> +</vcnote> +<vcnote id="defattrvalid"><head>Attribute Default Legal</head><p>The declared +default value must meet the lexical constraints of the declared attribute +type.</p> +</vcnote> +<vcnote id="FixedAttr"><head>Fixed Attribute Default</head><p>If an attribute +has a default value declared with the <kw>#FIXED</kw> keyword, instances of +that attribute must match the default value.</p> +</vcnote> +<p>Examples of attribute-list declarations:</p> +<eg><!ATTLIST termdef + id ID #REQUIRED + name CDATA #IMPLIED> +<!ATTLIST list + type (bullets|ordered|glossary) "ordered"> +<!ATTLIST form + method CDATA #FIXED "POST"></eg> +</div3> +<div3 id="AVNormalize" diff="chg"> +<head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E70">[E70]</loc>Attribute-Value +Normalization</head> +<p>Before the value of an attribute is passed to the application or checked +for validity, the XML processor must normalize the attribute value by applying +the algorithm below, or by using some other method such that the value passed +to the application is the same as that produced by the algorithm.</p> +<olist> +<item><p>All line breaks must have been normalized on input to #xA as described +in <specref ref="sec-line-ends"/>, so the rest of this algorithm operates +on text normalized in this way.</p></item> +<item><p>Begin with a normalized value consisting of the empty string.</p> +</item> +<item><p>For each character, entity reference, or character reference in the +unnormalized attribute value, beginning with the first and continuing to the +last, do the following:</p> +<ulist> +<item><p>For a character reference, append the referenced character to the +normalized value.</p></item> +<item><p>For an entity reference, recursively apply step 3 of this algorithm +to the replacement text of the entity.</p></item> +<item><p>For a white space character (#x20, #xD, #xA, #x9), append a space +character (#x20) to the normalized value.</p></item> +<item><p>For another character, append the character to the normalized value.</p> +</item> +</ulist> +</item> +</olist> +<p>If the attribute type is not CDATA, then the XML processor must further +process the normalized attribute value by discarding any leading and trailing +space (#x20) characters, and by replacing sequences of space (#x20) characters +by a single space (#x20) character.</p> +<p>Note that if the unnormalized attribute value contains a character reference +to a white space character other than space (#x20), the normalized value contains +the referenced character itself (#xD, #xA or #x9). This contrasts with the +case where the unnormalized value contains a white space character (not a +reference), which is replaced with a space character (#x20) in the normalized +value and also contrasts with the case where the unnormalized value contains +an entity reference whose replacement text contains a white space character; +being recursively processed, the white space character is replaced with a +space character (#x20) in the normalized value.</p> +<p>All attributes for which no declaration has been read should be treated +by a non-validating <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</loc>processor</phrase> +as if declared <kw>CDATA</kw>.</p> +<p>Following are examples of attribute normalization. Given the following +declarations:</p> +<eg><!ENTITY d "&#xD;"> +<!ENTITY a "&#xA;"> +<!ENTITY da "&#xD;&#xA;"></eg> +<p>the attribute specifications in the left column below would be normalized +to the character sequences of the middle column if the attribute <att>a</att> +is declared <kw>NMTOKENS</kw> and to those of the right columns if <att>a</att> +is declared <kw>CDATA</kw>.</p> +<table border="1" frame="border"><thead><tr><th>Attribute specification</th> +<th>a is NMTOKENS</th><th>a is CDATA</th></tr></thead><tbody><tr><td><eg>a=" + +xyz"</eg></td><td><code>x y z</code></td><td><code>#x20 #x20 x y z</code></td> +</tr><tr><td><eg>a="&d;&d;A&a;&a;B&da;"</eg></td><td><code>A +#x20 B</code></td><td><code>#x20 #x20 A #x20 #x20 B #x20 #x20</code></td> +</tr><tr><td><eg>a= +"&#xd;&#xd;A&#xa;&#xa;B&#xd;&#xa;"</eg></td><td><code>#xD +#xD A #xA #xA B #xD #xA</code></td><td><code>#xD #xD A #xA #xA B #xD #xD</code></td> +</tr></tbody></table> +<p>Note that the last example is invalid (but well-formed) if <att>a</att> +is declared to be of type <kw>NMTOKENS</kw>.</p> +</div3> +</div2> +<div2 id="sec-condition-sect"> +<head>Conditional Sections</head> +<p><termdef id="dt-cond-section" term="conditional section"> <term>Conditional +sections</term> are portions of the <termref def="dt-doctype">document type +declaration external subset</termref> which are included in, or excluded from, +the logical structure of the DTD based on the keyword which governs them.</termdef></p> +<scrap lang="ebnf"> +<head>Conditional Section</head> +<prodgroup pcw2="9" pcw4="14.5"> +<prod id="NT-conditionalSect"> +<lhs>conditionalSect</lhs><rhs><nt def="NT-includeSect">includeSect</nt> | <nt +def="NT-ignoreSect">ignoreSect</nt> </rhs> +</prod> +<prod id="NT-includeSect"> +<lhs>includeSect</lhs><rhs>'<![' S? 'INCLUDE' S? '[' <nt def="NT-extSubsetDecl">extSubsetDecl</nt> +']]>' </rhs><com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</loc></com> +<vc def="condsec-nesting" diff="add"/> +</prod> +<prod id="NT-ignoreSect"> +<lhs>ignoreSect</lhs><rhs>'<![' S? 'IGNORE' S? '[' <nt def="NT-ignoreSectContents">ignoreSectContents</nt>* +']]>'</rhs><com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</loc></com> +<vc def="condsec-nesting" diff="add"/> +</prod> +<prod id="NT-ignoreSectContents"> +<lhs>ignoreSectContents</lhs><rhs><nt def="NT-Ignore">Ignore</nt> ('<![' <nt +def="NT-ignoreSectContents">ignoreSectContents</nt> ']]>' <nt def="NT-Ignore">Ignore</nt>)*</rhs> +</prod> +<prod id="NT-Ignore"> +<lhs>Ignore</lhs><rhs><nt def="NT-Char">Char</nt>* - (<nt def="NT-Char">Char</nt>* +('<![' | ']]>') <nt def="NT-Char">Char</nt>*) </rhs> +</prod> +</prodgroup></scrap> +<vcnote id="condsec-nesting" diff="add"><head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</loc>Proper +Conditional Section/PE Nesting</head><p>If any of the "<code><![</code>", +"<code>[</code>", or "<code>]]></code>" of a conditional section is contained +in the replacement text for a parameter-entity reference, all of them must +be contained in the same replacement text.</p> +</vcnote> +<p>Like the internal and external DTD subsets, a conditional section may contain +one or more complete declarations, comments, processing instructions, or nested +conditional sections, intermingled with white space.</p> +<p>If the keyword of the conditional section is <kw>INCLUDE</kw>, then the +contents of the conditional section are part of the DTD. If the keyword of +the conditional section is <kw>IGNORE</kw>, then the contents of the conditional +section are not logically part of the DTD. <phrase diff="del"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</loc>Note that +for reliable parsing, the contents of even ignored conditional sections must +be read in order to detect nested conditional sections and ensure that the +end of the outermost (ignored) conditional section is properly detected.</phrase> +If a conditional section with a keyword of <kw>INCLUDE</kw> occurs within +a larger conditional section with a keyword of <kw>IGNORE</kw>, both the outer +and the inner conditional sections are ignored.<phrase diff="add"> <loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</loc>The contents +of an ignored conditional section are parsed by ignoring all characters after +the "<code>[</code>" following the keyword, except conditional section starts +"<code><![</code>" and ends "<code>]]></code>", until the matching conditional +section end is found. Parameter entity references are not recognized in this +process.</phrase></p> +<p>If the keyword of the conditional section is a parameter-entity reference, +the parameter entity must be replaced by its content before the processor +decides whether to include or ignore the conditional section.</p> +<p>An example:</p> +<eg><!ENTITY % draft 'INCLUDE' > +<!ENTITY % final 'IGNORE' > + +<![%draft;[ +<!ELEMENT book (comments*, title, body, supplements?)> +]]> +<![%final;[ +<!ELEMENT book (title, body, supplements?)> +]]></eg> +</div2> +<!-- +<div2 id='sec-pass-to-app'> +<head>XML Processor Treatment of Logical Structure</head> +<p>When an XML processor encounters a start-tag, it must make +at least the following information available to the application: +<ulist> +<item> +<p>the element type's generic identifier</p> +</item> +<item> +<p>the names of attributes known to apply to this element type +(validating processors must make available names of all attributes +declared for the element type; non-validating processors must +make available at least the names of the attributes for which +values are specified. +</p> +</item> +</ulist> +</p> +</div2> +--> +</div1> +<!-- &Entities; --> +<div1 id="sec-physical-struct"> +<head>Physical Structures</head> +<p><termdef id="dt-entity" term="Entity">An XML document may consist of one +or many storage units. <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E6">[E6]</loc>These +are called <term>entities</term>; they all have <term>content</term> and are +all (except for the <termref def="dt-docent">document entity</termref> and +the <termref def="dt-doctype">external DTD subset</termref>) identified by +entity <term>name</term></phrase>.</termdef> Each XML document has one entity +called the <termref def="dt-docent">document entity</termref>, which serves +as the starting point for the <termref def="dt-xml-proc">XML processor</termref> +and may contain the whole document.</p> +<p>Entities may be either parsed or unparsed. <termdef id="dt-parsedent" term="Text Entity">A <term>parsed +entity's</term> contents are referred to as its <termref def="dt-repltext">replacement +text</termref>; this <termref def="dt-text">text</termref> is considered an +integral part of the document.</termdef></p> +<p><termdef id="dt-unparsed" term="Unparsed Entity">An <term>unparsed entity</term> +is a resource whose contents may or may not be <termref def="dt-text">text</termref>, +and if text, <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E25">[E25]</loc>may +be other than</phrase> XML. Each unparsed entity has an associated <termref +def="dt-notation">notation</termref>, identified by name. Beyond a requirement +that an XML processor make the identifiers for the entity and notation available +to the application, XML places no constraints on the contents of unparsed +entities.</termdef></p> +<p>Parsed entities are invoked by name using entity references; unparsed entities +by name, given in the value of <kw>ENTITY</kw> or <kw>ENTITIES</kw> attributes.</p> +<p><termdef id="gen-entity" term="general entity"><term>General entities</term> +are entities for use within the document content. In this specification, general +entities are sometimes referred to with the unqualified term <emph>entity</emph> +when this leads to no ambiguity.</termdef> <termdef id="dt-PE" term="Parameter entity"><phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E53">[E53]</loc><term>Parameter +entities</term></phrase> are parsed entities for use within the DTD.</termdef> +These two types of entities use different forms of reference and are recognized +in different contexts. Furthermore, they occupy different namespaces; a parameter +entity and a general entity with the same name are two distinct entities.</p> +<div2 id="sec-references"> +<head>Character and Entity References</head> +<p><termdef id="dt-charref" term="Character Reference"> A <term>character +reference</term> refers to a specific character in the ISO/IEC 10646 character +set, for example one not directly accessible from available input devices.</termdef></p> +<scrap lang="ebnf"> +<head>Character Reference</head> +<prod id="NT-CharRef"> +<lhs>CharRef</lhs><rhs>'&#' [0-9]+ ';' </rhs> +<rhs>| '&hcro;' [0-9a-fA-F]+ ';'</rhs><wfc def="wf-Legalchar"/> +</prod> +</scrap> +<wfcnote id="wf-Legalchar"><head>Legal Character</head><p>Characters referred +to using character references must match the production for <termref def="NT-Char">Char</termref>.</p> +</wfcnote> +<p>If the character reference begins with <quote><code>&#x</code></quote>, +the digits and letters up to the terminating <code>;</code> provide a hexadecimal +representation of the character's code point in ISO/IEC 10646. If it begins +just with <quote><code>&#</code></quote>, the digits up to the terminating <code>;</code> +provide a decimal representation of the character's code point.</p> +<p><termdef id="dt-entref" term="Entity Reference">An <term>entity reference</term> +refers to the content of a named entity.</termdef> <termdef id="dt-GERef" +term="General Entity Reference">References to parsed general entities use +ampersand (<code>&</code>) and semicolon (<code>;</code>) as delimiters.</termdef> <termdef +id="dt-PERef" term="Parameter-entity reference"> <term>Parameter-entity references</term> +use percent-sign (<code>%</code>) and semicolon (<code>;</code>) as delimiters.</termdef></p> +<scrap lang="ebnf"> +<head>Entity Reference</head> +<prod id="NT-Reference"> +<lhs>Reference</lhs><rhs><nt def="NT-EntityRef">EntityRef</nt> | <nt def="NT-CharRef">CharRef</nt></rhs> +</prod> +<prod id="NT-EntityRef"> +<lhs>EntityRef</lhs><rhs>'&' <nt def="NT-Name">Name</nt> ';'</rhs><wfc +def="wf-entdeclared"/><vc def="vc-entdeclared"/><wfc def="textent"/><wfc def="norecursion"/> +</prod> +<prod id="NT-PEReference"> +<lhs>PEReference</lhs><rhs>'%' <nt def="NT-Name">Name</nt> ';'</rhs><vc def="vc-entdeclared"/> +<wfc def="norecursion"/><wfc def="indtd"/> +</prod> +</scrap> +<wfcnote id="wf-entdeclared"><head>Entity Declared</head><p>In a document +without any DTD, a document with only an internal DTD subset which contains +no parameter entity references, or a document with <quote><code>standalone='yes'</code></quote>, <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E34">[E34]</loc>for +an entity reference that does not occur within the external subset or a parameter +entity, the <nt def="NT-Name">Name</nt> given in the entity reference must <termref +def="dt-match">match</termref> that in an <titleref href="#sec-entity-decl">entity +declaration</titleref> that does not occur within the external subset or a +parameter entity</phrase>, except that well-formed documents need not declare +any of the following entities: &magicents;. <phrase diff="del"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E29">[E29]</loc>The declaration +of a parameter entity must precede any reference to it. Similarly, </phrase>The +declaration of a general entity must precede any reference to it which appears +in a default value in an attribute-list declaration.</p> +<p>Note that if entities are declared in the external subset or in external +parameter entities, a non-validating processor is <titleref href="#include-if-valid">not +obligated to</titleref> read and process their declarations; for such documents, +the rule that an entity must be declared is a well-formedness constraint only +if <titleref href="#sec-rmd">standalone='yes'</titleref>.</p> +</wfcnote> +<vcnote id="vc-entdeclared"><head>Entity Declared</head><p>In a document with +an external subset or external parameter entities with <quote><code>standalone='no'</code></quote>, +the <nt def="NT-Name">Name</nt> given in the entity reference must <termref +def="dt-match">match</termref> that in an <titleref href="#sec-entity-decl">entity +declaration</titleref>. For interoperability, valid documents should declare +the entities &magicents;, in the form specified in <specref ref="sec-predefined-ent"/>. +The declaration of a parameter entity must precede any reference to it. Similarly, +the declaration of a general entity must precede any <phrase diff="chg"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E92">[E92]</loc>attribute-list +declaration containing a default value with a direct or indirect reference +to that general entity.</phrase></p> +</vcnote> +<!-- FINAL EDIT: is this duplication too clumsy? --> +<wfcnote id="textent"><head>Parsed Entity</head><p>An entity reference must +not contain the name of an <termref def="dt-unparsed">unparsed entity</termref>. +Unparsed entities may be referred to only in <termref def="dt-attrval">attribute +values</termref> declared to be of type <kw>ENTITY</kw> or <kw>ENTITIES</kw>.</p> +</wfcnote> +<wfcnote id="norecursion"><head>No Recursion</head><p>A parsed entity must +not contain a recursive reference to itself, either directly or indirectly.</p> +</wfcnote> +<wfcnote id="indtd"><head>In DTD</head><p>Parameter-entity references may +only appear in the <termref def="dt-doctype">DTD</termref>.</p> +</wfcnote> +<p>Examples of character and entity references:</p> +<eg>Type <key>less-than</key> (&hcro;3C;) to save options. +This document was prepared on &docdate; and +is classified &security-level;.</eg> +<p>Example of a parameter-entity reference:</p> +<eg><![CDATA[<!-- declare the parameter entity "ISOLat2"... --> +<!ENTITY % ISOLat2 + SYSTEM "http://www.xml.com/iso/isolat2-xml.entities" > +<!-- ... now reference it. --> +%ISOLat2;]]></eg> +</div2> +<div2 id="sec-entity-decl"> +<head>Entity Declarations</head> +<p><termdef id="dt-entdecl" term="entity declaration"> Entities are declared +thus:</termdef></p> +<scrap lang="ebnf"> +<head>Entity Declaration</head> +<prodgroup pcw2="5" pcw4="18.5"> +<prod id="NT-EntityDecl"> +<lhs>EntityDecl</lhs><rhs><nt def="NT-GEDecl">GEDecl</nt><!--</rhs><com>General entities</com> +<rhs>--> | <nt def="NT-PEDecl">PEDecl</nt></rhs> +<!--<com>Parameter entities</com>--> +</prod> +<prod id="NT-GEDecl"> +<lhs>GEDecl</lhs><rhs>'<!ENTITY' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt> <nt +def="NT-S">S</nt> <nt def="NT-EntityDef">EntityDef</nt> <nt def="NT-S">S</nt>? +'>'</rhs> +</prod> +<prod id="NT-PEDecl"> +<lhs>PEDecl</lhs><rhs>'<!ENTITY' <nt def="NT-S">S</nt> '%' <nt def="NT-S">S</nt> <nt +def="NT-Name">Name</nt> <nt def="NT-S">S</nt> <nt def="NT-PEDef">PEDef</nt> <nt +def="NT-S">S</nt>? '>'</rhs> +<!--<com>Parameter entities</com>--> +</prod> +<prod id="NT-EntityDef"> +<lhs>EntityDef</lhs><rhs><nt def="NT-EntityValue">EntityValue</nt> <!--</rhs> +<rhs>-->| (<nt def="NT-ExternalID">ExternalID</nt> <nt def="NT-NDataDecl">NDataDecl</nt>?)</rhs> +<!-- <nt def='NT-ExternalDef'>ExternalDef</nt></rhs> --> +</prod> +<!-- FINAL EDIT: what happened to WFs here? --> +<prod id="NT-PEDef"> +<lhs>PEDef</lhs><rhs><nt def="NT-EntityValue">EntityValue</nt> | <nt def="NT-ExternalID">ExternalID</nt></rhs> +</prod> +</prodgroup></scrap> +<p>The <nt def="NT-Name">Name</nt> identifies the entity in an <termref def="dt-entref">entity +reference</termref> or, in the case of an unparsed entity, in the value of +an <kw>ENTITY</kw> or <kw>ENTITIES</kw> attribute. If the same entity is declared +more than once, the first declaration encountered is binding; at user option, +an XML processor may issue a warning if entities are declared multiple times.</p> +<div3 id="sec-internal-ent"> +<head>Internal Entities</head> +<p><termdef id="dt-internent" term="Internal Entity Replacement Text">If the +entity definition is an <nt def="NT-EntityValue">EntityValue</nt>, the defined +entity is called an <term>internal entity</term>. There is no separate physical +storage object, and the content of the entity is given in the declaration.</termdef> +Note that some processing of entity and character references in the <termref +def="dt-litentval">literal entity value</termref> may be required to produce +the correct <termref def="dt-repltext">replacement text</termref>: see <specref +ref="intern-replacement"/>.</p> +<p>An internal entity is a <termref def="dt-parsedent">parsed entity</termref>.</p> +<p>Example of an internal entity declaration:</p> +<eg><!ENTITY Pub-Status "This is a pre-release of the + specification."></eg> +</div3> +<div3 id="sec-external-ent"> +<head>External Entities</head> +<p><termdef id="dt-extent" term="External Entity">If the entity is not internal, +it is an <term>external entity</term>, declared as follows:</termdef></p> +<scrap lang="ebnf"> +<head>External Entity Declaration</head> +<!-- +<prod id='NT-ExternalDef'><lhs>ExternalDef</lhs> +<rhs></prod> --> +<prod id="NT-ExternalID"> +<lhs>ExternalID</lhs><rhs>'SYSTEM' <nt def="NT-S">S</nt> <nt def="NT-SystemLiteral">SystemLiteral</nt></rhs> +<rhs>| 'PUBLIC' <nt def="NT-S">S</nt> <nt def="NT-PubidLiteral">PubidLiteral</nt> <nt +def="NT-S">S</nt> <nt def="NT-SystemLiteral">SystemLiteral</nt> </rhs> +</prod> +<prod id="NT-NDataDecl"> +<lhs>NDataDecl</lhs><rhs><nt def="NT-S">S</nt> 'NDATA' <nt def="NT-S">S</nt> <nt +def="NT-Name">Name</nt></rhs><vc def="not-declared"/> +</prod> +</scrap> +<p>If the <nt def="NT-NDataDecl">NDataDecl</nt> is present, this is a general <termref +def="dt-unparsed">unparsed entity</termref>; otherwise it is a parsed entity.</p> +<vcnote id="not-declared"><head>Notation Declared</head><p>The <nt def="NT-Name">Name</nt> +must match the declared name of a <termref def="dt-notation">notation</termref>.</p> +</vcnote> +<p><phrase diff="chg"><termdef id="dt-sysid" term="System Identifier">The <nt +def="NT-SystemLiteral">SystemLiteral</nt> is called the entity's <term>system +identifier</term>. It is a <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E88">[E88]</loc>URI +reference</phrase><phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</loc> +(as defined in <bibref ref="rfc2396"/>, updated by <bibref ref="rfc2732"/>)</phrase>, <loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E76">[E76]</loc>meant +to be dereferenced to obtain input for the XML processor to construct the +entity's replacement text.</termdef> It is an error for a fragment identifier +(beginning with a <code>#</code> character) to be part of a system identifier.</phrase> +Unless otherwise provided by information outside the scope of this specification +(e.g. a special XML element type defined by a particular DTD, or a processing +instruction defined by a particular application specification), relative URIs +are relative to the location of the resource within which the entity declaration +occurs. A URI might thus be relative to the <termref def="dt-docent">document +entity</termref>, to the entity containing the <termref def="dt-doctype">external +DTD subset</termref>, or to some other <termref def="dt-extent">external parameter +entity</termref>.</p> +<p diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E78">[E78]</loc>URI +references require encoding and escaping of certain characters. The disallowed +characters include all non-ASCII characters, plus the excluded characters +listed in Section 2.4 of <bibref ref="rfc2396"/>, except for the number sign +(<code>#</code>) and percent sign (<code>%</code>) characters and the square +bracket characters re-allowed in <bibref ref="rfc2732"/>. Disallowed characters +must be escaped as follows:</p> +<olist diff="add"> +<item><p>Each disallowed character is converted to UTF-8 <bibref ref="rfc2279"/> +as one or more bytes.</p></item> +<item><p>Any octets corresponding to a disallowed character are escaped with +the URI escaping mechanism (that is, converted to <code>%</code><var>HH</var>, +where HH is the hexadecimal notation of the byte value).</p></item> +<item><p>The original character is replaced by the resulting character sequence.</p> +</item> +</olist> +<p><termdef id="dt-pubid" term="Public identifier"> In addition to a system +identifier, an external identifier may include a <term>public identifier</term>.</termdef> +An XML processor attempting to retrieve the entity's content may use the public +identifier to try to generate an alternative <phrase diff="chg"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E88">[E88]</loc>URI reference</phrase>. +If the processor is unable to do so, it must use the <phrase diff="chg"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E88">[E88]</loc>URI +reference</phrase> specified in the system literal. Before a match is attempted, +all strings of white space in the public identifier must be normalized to +single space characters (#x20), and leading and trailing white space must +be removed.</p> +<p>Examples of external entity declarations:</p> +<eg><!ENTITY open-hatch + SYSTEM "http://www.textuality.com/boilerplate/OpenHatch.xml"> +<!ENTITY open-hatch + PUBLIC "-//Textuality//TEXT Standard open-hatch boilerplate//EN" + "http://www.textuality.com/boilerplate/OpenHatch.xml"> +<!ENTITY hatch-pic + SYSTEM "../grafix/OpenHatch.gif" + NDATA gif ></eg> +</div3> +</div2> +<div2 id="TextEntities"> +<head>Parsed Entities</head> +<div3 id="sec-TextDecl"> +<head>The Text Declaration</head> +<p>External parsed entities <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E107">[E107]</loc>should</phrase +> each begin with a <term>text declaration</term>.</p> +<scrap lang="ebnf"> +<head>Text Declaration</head> +<prodgroup pcw4="12.5" pcw5="13"> +<prod id="NT-TextDecl"> +<lhs>TextDecl</lhs><rhs>&pio; <nt def="NT-VersionInfo">VersionInfo</nt>? <nt +def="NT-EncodingDecl">EncodingDecl</nt> <nt def="NT-S">S</nt>? &pic;</rhs> +</prod> +</prodgroup></scrap> +<p>The text declaration must be provided literally, not by reference to a +parsed entity. No text declaration may appear at any position other than the +beginning of an external parsed entity. <phrase diff="add"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E94">[E94]</loc>The text declaration +in an external parsed entity is not considered part of its <termref def="dt-repltext">replacement +text</termref>.</phrase></p> +</div3> +<div3 id="wf-entities"> +<head>Well-Formed Parsed Entities</head> +<p>The document entity is well-formed if it matches the production labeled <nt +def="NT-document">document</nt>. An external general parsed entity is well-formed +if it matches the production labeled <nt def="NT-extParsedEnt">extParsedEnt</nt>. <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc>All +external parameter entities are well-formed by definition.</phrase></p> +<scrap lang="ebnf"> +<head>Well-Formed External Parsed Entity</head> +<prod id="NT-extParsedEnt"> +<lhs>extParsedEnt</lhs><rhs><nt def="NT-TextDecl">TextDecl</nt>? <nt def="NT-content">content</nt></rhs> +</prod> +<prod id="NT-extPE" diff="del"> +<lhs>extPE</lhs><rhs><nt def="NT-TextDecl">TextDecl</nt>? <nt def="NT-extSubsetDecl">extSubsetDecl</nt></rhs> +<com><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</loc></com> +</prod> +</scrap> +<p>An internal general parsed entity is well-formed if its replacement text +matches the production labeled <nt def="NT-content">content</nt>. All internal +parameter entities are well-formed by definition.</p> +<p>A consequence of well-formedness in entities is that the logical and physical +structures in an XML document are properly nested; no <termref def="dt-stag">start-tag</termref>, <termref +def="dt-etag">end-tag</termref>, <termref def="dt-empty">empty-element tag</termref>, <termref +def="dt-element">element</termref>, <termref def="dt-comment">comment</termref>, <termref +def="dt-pi">processing instruction</termref>, <termref def="dt-charref">character +reference</termref>, or <termref def="dt-entref">entity reference</termref> +can begin in one entity and end in another.</p> +</div3> +<div3 id="charencoding"> +<head>Character Encoding in Entities</head> +<p>Each external parsed entity in an XML document may use a different encoding +for its characters. All XML processors must be able to read entities in <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E56">[E56]</loc>both +the UTF-8 and UTF-16 encodings.</phrase> <phrase diff="add"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E77">[E77]</loc>The terms <quote>UTF-8</quote> +and <quote>UTF-16</quote> in this specification do not apply to character +encodings with any other labels, even if the encodings or labels are very +similar to UTF-8 or UTF-16.</phrase></p> +<p>Entities encoded in UTF-16 must begin with the Byte Order Mark described +by <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc>Annex +F of <bibref ref="ISO10646"/>, Annex H of <bibref ref="ISO10646-2000"/>, section +2.4 of <bibref ref="Unicode"/>, and section 2.7 of <bibref ref="Unicode3"/></phrase> +(the ZERO WIDTH NO-BREAK SPACE character, #xFEFF). This is an encoding signature, +not part of either the markup or the character data of the XML document. XML +processors must be able to use this character to differentiate between UTF-8 +and UTF-16 encoded documents.</p> +<p>Although an XML processor is required to read only entities in the UTF-8 +and UTF-16 encodings, it is recognized that other encodings are used around +the world, and it may be desired for XML processors to read entities that +use them. <phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E47">[E47]</loc>In +the absence of external character encoding information (such as MIME headers),</phrase> +parsed entities which are stored in an encoding other than UTF-8 or UTF-16 +must begin with a text declaration <phrase diff="add">(see <specref ref="sec-TextDecl"/>) </phrase>containing +an encoding declaration:</p> +<scrap lang="ebnf"> +<head>Encoding Declaration</head> +<prod id="NT-EncodingDecl"> +<lhs>EncodingDecl</lhs><rhs><nt def="NT-S">S</nt> 'encoding' <nt def="NT-Eq">Eq</nt> +('"' <nt def="NT-EncName">EncName</nt> '"' | "'" <nt def="NT-EncName">EncName</nt> +"'" ) </rhs> +</prod> +<prod id="NT-EncName"> +<lhs>EncName</lhs><rhs>[A-Za-z] ([A-Za-z0-9._] | '-')*</rhs><com>Encoding +name contains only Latin characters</com> +</prod> +</scrap> +<p>In the <termref def="dt-docent">document entity</termref>, the encoding +declaration is part of the <termref def="dt-xmldecl">XML declaration</termref>. +The <nt def="NT-EncName">EncName</nt> is the name of the encoding used.</p> +<!-- FINAL EDIT: check name of IANA and charset names --> +<p>In an encoding declaration, the values <quote><code>UTF-8</code></quote>, <quote><code>UTF-16</code></quote>, <quote><code>ISO-10646-UCS-2</code +></quote>, and <quote><code>ISO-10646-UCS-4</code></quote> should be used +for the various encodings and transformations of Unicode / ISO/IEC 10646, +the values <quote><code>ISO-8859-1</code></quote>, <quote><code>ISO-8859-2</code></quote>, +... <loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E106">[E106]</loc><phrase +diff="chg"><quote><code>ISO-8859-</code><var>n</var></quote> (where <var>n</var> +is the part number)</phrase> should be used for the parts of ISO 8859, and +the values <quote><code>ISO-2022-JP</code></quote>, <quote><code>Shift_JIS</code></quote>, +and <quote><code>EUC-JP</code></quote> should be used for the various encoded +forms of JIS X-0208-1997. <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E57">[E57]</loc>It +is recommended that character encodings registered (as <emph>charset</emph>s) +with the Internet Assigned Numbers Authority <phrase diff="chg"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</loc><bibref ref="IANA"/></phrase>, +other than those just listed, be referred to using their registered names; +other encodings should use names starting with an <quote>x-</quote> prefix. +XML processors should match character encoding names in a case-insensitive +way and should either interpret an IANA-registered name as the encoding registered +at IANA for that name or treat it as unknown (processors are, of course, not +required to support all IANA-registered encodings).</phrase></p> +<p>In the absence of information provided by an external transport protocol +(e.g. HTTP or MIME), it is an <termref def="dt-error">error</termref> for +an entity including an encoding declaration to be presented to the XML processor +in an encoding other than that named in the declaration, <phrase diff="del"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E5">[E5]</loc>for +an encoding declaration to occur other than at the beginning of an external +entity, </phrase>or for an entity which begins with neither a Byte Order Mark +nor an encoding declaration to use an encoding other than UTF-8. Note that +since ASCII is a subset of UTF-8, ordinary ASCII entities do not strictly +need an encoding declaration.</p> +<p diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E5">[E5]</loc>It +is <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E36">[E36]</loc>a +fatal</phrase> error for a <nt def="NT-TextDecl">TextDecl</nt> to occur other +than at the beginning of an external entity.</p> +<p>It is a <termref def="dt-fatal">fatal error</termref> when an XML processor +encounters an entity with an encoding that it is unable to process. <phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E79">[E79]</loc>It +is a fatal error if an XML entity is determined (via default, encoding declaration, +or higher-level protocol) to be in a certain encoding but contains octet sequences +that are not legal in that encoding. It is also a fatal error if an XML entity +contains no encoding declaration and its content is not legal UTF-8 or UTF-16.</phrase></p> +<p>Examples of <phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E23">[E23]</loc>text +declarations containing </phrase>encoding declarations:</p> +<eg><?xml encoding='UTF-8'?> +<?xml encoding='EUC-JP'?></eg> +</div3> +</div2> +<div2 id="entproc"> +<head>XML Processor Treatment of Entities and References</head> +<p>The table below summarizes the contexts in which character references, +entity references, and invocations of unparsed entities might appear and the +required behavior of an <termref def="dt-xml-proc">XML processor</termref> +in each case. The labels in the leftmost column describe the recognition context: <glist> +<gitem><label>Reference in Content</label> +<def> +<p>as a reference anywhere after the <termref def="dt-stag">start-tag</termref> +and before the <termref def="dt-etag">end-tag</termref> of an element; corresponds +to the nonterminal <nt def="NT-content">content</nt>.</p> +</def></gitem> +<gitem><label>Reference in Attribute Value</label> +<def> +<p>as a reference within either the value of an attribute in a <termref def="dt-stag">start-tag</termref>, +or a default value in an <termref def="dt-attdecl">attribute declaration</termref>; +corresponds to the nonterminal <nt def="NT-AttValue">AttValue</nt>.</p> +</def></gitem> +<gitem><label>Occurs as Attribute Value</label> +<def> +<p>as a <nt def="NT-Name">Name</nt>, not a reference, appearing either as +the value of an attribute which has been declared as type <kw>ENTITY</kw>, +or as one of the space-separated tokens in the value of an attribute which +has been declared as type <kw>ENTITIES</kw>.</p> +</def></gitem> +<gitem><label>Reference in Entity Value</label> +<def> +<p>as a reference within a parameter or internal entity's <termref def="dt-litentval">literal +entity value</termref> in the entity's declaration; corresponds to the nonterminal <nt +def="NT-EntityValue">EntityValue</nt>.</p> +</def></gitem> +<gitem><label>Reference in DTD</label> +<def> +<p diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</loc>as +a reference within either the internal or external subsets of the <termref +def="dt-doctype">DTD</termref>, but outside of an <nt def="NT-EntityValue">EntityValue</nt>, <nt +def="NT-AttValue">AttValue</nt>, <nt def="NT-PI">PI</nt>, <nt def="NT-Comment">Comment</nt>, <nt +def="NT-SystemLiteral">SystemLiteral</nt>, <nt def="NT-PubidLiteral">PubidLiteral</nt>, +or the contents of an ignored conditional section (see <specref ref="sec-condition-sect"/>).</p> +<p>.</p> +</def></gitem> +</glist></p> +<table border="1" frame="border" cellpadding="7"><tbody align="center"><tr> +<td rowspan="2" colspan="1"></td><td colspan="4" align="center" valign="bottom">Entity +Type</td><td rowspan="2" align="center">Character</td></tr><tr align="center" +valign="bottom"><td>Parameter</td><td>Internal General</td><td>External Parsed +General</td><td>Unparsed</td></tr><tr align="center" valign="middle"><td align="right">Reference +in Content</td><td><titleref href="#not-recognized">Not recognized</titleref></td> +<td><titleref href="#included">Included</titleref></td><td><titleref href="#include-if-valid">Included +if validating</titleref></td><td><titleref href="#forbidden">Forbidden</titleref></td> +<td><titleref href="#included">Included</titleref></td></tr><tr align="center" +valign="middle"><td align="right">Reference in Attribute Value</td><td><titleref +href="#not-recognized">Not recognized</titleref></td><td><titleref href="#inliteral">Included +in literal</titleref></td><td><titleref href="#forbidden">Forbidden</titleref></td> +<td><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E51">[E51]</loc><titleref +diff="chg" href="#forbidden">Forbidden</titleref></td><td><titleref href="#included">Included</titleref></td> +</tr><tr align="center" valign="middle"><td align="right">Occurs as Attribute +Value</td><td><titleref href="#not-recognized">Not recognized</titleref></td> +<td><titleref href="#forbidden">Forbidden</titleref></td><td><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E51">[E51]</loc><titleref +diff="chg" href="#forbidden">Forbidden</titleref></td><td><titleref href="#notify">Notify</titleref></td> +<td><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E51">[E51]</loc><titleref +diff="chg" href="#not-recognized">Not recognized</titleref></td></tr><tr align="center" +valign="middle"><td align="right">Reference in EntityValue</td><td><titleref +href="#inliteral">Included in literal</titleref></td><td><titleref href="#bypass">Bypassed</titleref></td> +<td><titleref href="#bypass">Bypassed</titleref></td><td><titleref href="#forbidden">Forbidden</titleref></td> +<td><titleref href="#included">Included</titleref></td></tr><tr align="center" +valign="middle"><td align="right">Reference in DTD</td><td><titleref href="#as-PE">Included +as PE</titleref></td><td><titleref href="#forbidden">Forbidden</titleref></td> +<td><titleref href="#forbidden">Forbidden</titleref></td><td><titleref href="#forbidden">Forbidden</titleref></td> +<td><titleref href="#forbidden">Forbidden</titleref></td></tr></tbody></table> +<div3 id="not-recognized"> +<head>Not Recognized</head> +<p>Outside the DTD, the <code>%</code> character has no special significance; +thus, what would be parameter entity references in the DTD are not recognized +as markup in <nt def="NT-content">content</nt>. Similarly, the names of unparsed +entities are not recognized except when they appear in the value of an appropriately +declared attribute.</p> +</div3> +<div3 id="included"> +<head>Included</head> +<p><termdef id="dt-include" term="Include">An entity is <term>included</term> +when its <termref def="dt-repltext">replacement text</termref> is retrieved +and processed, in place of the reference itself, as though it were part of +the document at the location the reference was recognized.</termdef> The replacement +text may contain both <termref def="dt-chardata">character data</termref> +and (except for parameter entities) <termref def="dt-markup">markup</termref>, +which must be recognized in the usual way<phrase diff="del"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E65">[E65]</loc>, except that +the replacement text of entities used to escape markup delimiters (the entities &magicents;) +is always treated as data</phrase>. (The string <quote><code>AT&amp;T;</code></quote> +expands to <quote><code>AT&T;</code></quote> and the remaining ampersand +is not recognized as an entity-reference delimiter.) A character reference +is <term>included</term> when the indicated character is processed in place +of the reference itself. </p> +</div3> +<div3 id="include-if-valid"> +<head>Included If Validating</head> +<p>When an XML processor recognizes a reference to a parsed entity, in order +to <termref def="dt-valid">validate</termref> the document, the processor +must <termref def="dt-include">include</termref> its replacement text. If +the entity is external, and the processor is not attempting to validate the +XML document, the processor <termref def="dt-may">may</termref>, but need +not, include the entity's replacement text. If a non-validating <phrase diff="chg"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</loc>processor</phrase> +does not include the replacement text, it must inform the application that +it recognized, but did not read, the entity.</p> +<p>This rule is based on the recognition that the automatic inclusion provided +by the SGML and XML entity mechanism, primarily designed to support modularity +in authoring, is not necessarily appropriate for other applications, in particular +document browsing. Browsers, for example, when encountering an external parsed +entity reference, might choose to provide a visual indication of the entity's +presence and retrieve it for display only on demand.</p> +</div3> +<div3 id="forbidden"> +<head>Forbidden</head> +<p>The following are forbidden, and constitute <termref def="dt-fatal">fatal</termref> +errors:</p> +<ulist> +<item><p>the appearance of a reference to an <termref def="dt-unparsed">unparsed +entity</termref>.</p></item> +<item><p>the appearance of any character or general-entity reference in the +DTD except within an <nt def="NT-EntityValue">EntityValue</nt> or <nt def="NT-AttValue">AttValue</nt>.</p> +</item> +<item><p>a reference to an external entity in an attribute value.</p></item> +</ulist> +</div3> +<div3 id="inliteral"> +<head>Included in Literal</head> +<p>When an <termref def="dt-entref">entity reference</termref> appears in +an attribute value, or a parameter entity reference appears in a literal entity +value, its <termref def="dt-repltext">replacement text</termref> is processed +in place of the reference itself as though it were part of the document at +the location the reference was recognized, except that a single or double +quote character in the replacement text is always treated as a normal data +character and will not terminate the literal. For example, this is well-formed:</p> +<eg diff="chg"><!-- <loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E4">[E4]</loc> --> +<![CDATA[<!ENTITY % YN '"Yes"' > +<!ENTITY WhatHeSaid "He said %YN;" >]]></eg> +<p>while this is not:</p> +<eg><!ENTITY EndAttr "27'" > +<element attribute='a-&EndAttr;></eg> +</div3> +<div3 id="notify"> +<head>Notify</head> +<p>When the name of an <termref def="dt-unparsed">unparsed entity</termref> +appears as a token in the value of an attribute of declared type <kw>ENTITY</kw> +or <kw>ENTITIES</kw>, a validating processor must inform the application of +the <termref def="dt-sysid">system</termref> and <termref def="dt-pubid">public</termref> +(if any) identifiers for both the entity and its associated <termref def="dt-notation">notation</termref>.</p> +</div3> +<div3 id="bypass"> +<head>Bypassed</head> +<p>When a general entity reference appears in the <nt def="NT-EntityValue">EntityValue</nt> +in an entity declaration, it is bypassed and left as is.</p> +</div3> +<div3 id="as-PE"> +<head>Included as PE</head> +<p>Just as with external parsed entities, parameter entities need only be <titleref +href="#include-if-valid">included if validating</titleref>. When a parameter-entity +reference is recognized in the DTD and included, its <termref def="dt-repltext">replacement +text</termref> is enlarged by the attachment of one leading and one following +space (#x20) character; the intent is to constrain the replacement text of +parameter entities to contain an integral number of grammatical tokens in +the DTD. <phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E96">[E96]</loc>This +behavior does not apply to parameter entity references within entity values; +these are described in <specref ref="inliteral"/>.</phrase></p> +</div3> +</div2> +<div2 id="intern-replacement"> +<head>Construction of Internal Entity Replacement Text</head> +<p>In discussing the treatment of internal entities, it is useful to distinguish +two forms of the entity's value. <termdef id="dt-litentval" term="Literal Entity Value">The <term>literal +entity value</term> is the quoted string actually present in the entity declaration, +corresponding to the non-terminal <nt def="NT-EntityValue">EntityValue</nt>.</termdef> <termdef +id="dt-repltext" term="Replacement Text">The <term>replacement text</term> +is the content of the entity, after replacement of character references and +parameter-entity references.</termdef></p> +<p>The literal entity value as given in an internal entity declaration (<nt +def="NT-EntityValue">EntityValue</nt>) may contain character, parameter-entity, +and general-entity references. Such references must be contained entirely +within the literal entity value. The actual replacement text that is <termref +def="dt-include">included</termref> as described above must contain the <emph>replacement +text</emph> of any parameter entities referred to, and must contain the character +referred to, in place of any character references in the literal entity value; +however, general-entity references must be left as-is, unexpanded. For example, +given the following declarations:</p> +<eg><![CDATA[<!ENTITY % pub "Éditions Gallimard" > +<!ENTITY rights "All rights reserved" > +<!ENTITY book "La Peste: Albert Camus, +© 1947 %pub;. &rights;" >]]></eg> +<p>then the replacement text for the entity <quote><code>book</code></quote> +is:</p> +<eg>La Peste: Albert Camus, +© 1947 Éditions Gallimard. &rights;</eg> +<p>The general-entity reference <quote><code>&rights;</code></quote> would +be expanded should the reference <quote><code>&book;</code></quote> appear +in the document's content or an attribute value.</p> +<p>These simple rules may have complex interactions; for a detailed discussion +of a difficult example, see <specref ref="sec-entexpand"/>.</p> +</div2> +<div2 id="sec-predefined-ent"> +<head>Predefined Entities</head> +<p><termdef id="dt-escape" term="escape">Entity and character references can +both be used to <term>escape</term> the left angle bracket, ampersand, and +other delimiters. A set of general entities (&magicents;) is specified for +this purpose. Numeric character references may also be used; they are expanded +immediately when recognized and must be treated as character data, so the +numeric character references <quote><code>&#60;</code></quote> and <quote><code>&#38;</code></quote> +may be used to escape <code><</code> and <code>&</code> when they occur +in character data.</termdef></p> +<p>All XML processors must recognize these entities whether they are declared +or not. <termref def="dt-interop">For interoperability</termref>, valid XML +documents should declare these entities, like any others, before using them. <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E80">[E80]</loc>If +the entities <code>lt</code> or <code>amp</code> are declared, they must be +declared as internal entities whose replacement text is a character reference +to the <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E103">[E103]</loc>respective +character (less-than sign or ampersand)</phrase> being escaped; the double +escaping is required for these entities so that references to them produce +a well-formed result. If the entities <code>gt</code>, <code>apos</code>, +or <code>quot</code> are declared, they must be declared as internal entities +whose replacement text is the single character being escaped (or a character +reference to that character; the double escaping here is unnecessary but harmless). +For example:</phrase></p> +<eg><![CDATA[<!ENTITY lt "&#60;"> +<!ENTITY gt ">"> +<!ENTITY amp "&#38;"> +<!ENTITY apos "'"> +<!ENTITY quot """>]]></eg> +<p diff="del">Note that the <code><</code> and <code>&</code> characters +in the declarations of <quote><code>lt</code></quote> and <quote><code>amp</code></quote> +are doubly escaped to meet the requirement that entity replacement be well-formed.</p> +</div2> +<div2 id="Notations"> +<head>Notation Declarations</head> +<p><termdef id="dt-notation" term="Notation"><term>Notations</term> identify +by name the format of <termref def="dt-extent">unparsed entities</termref>, +the format of elements which bear a notation attribute, or the application +to which a <termref def="dt-pi">processing instruction</termref> is addressed.</termdef></p> +<p><termdef id="dt-notdecl" term="Notation Declaration"> <term>Notation declarations</term> +provide a name for the notation, for use in entity and attribute-list declarations +and in attribute specifications, and an external identifier for the notation +which may allow an XML processor or its client application to locate a helper +application capable of processing data in the given notation.</termdef></p> +<scrap lang="ebnf"> +<head>Notation Declarations</head> +<prod id="NT-NotationDecl"> +<lhs>NotationDecl</lhs><rhs>'<!NOTATION' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt> <nt +def="NT-S">S</nt> (<nt def="NT-ExternalID">ExternalID</nt> | <nt def="NT-PublicID">PublicID</nt>) <nt +def="NT-S">S</nt>? '>'</rhs><vc def="UniqueNotationName" diff="add"/> +</prod> +<prod id="NT-PublicID"> +<lhs>PublicID</lhs><rhs>'PUBLIC' <nt def="NT-S">S</nt> <nt def="NT-PubidLiteral">PubidLiteral</nt> </rhs> +</prod> +</scrap> +<vcnote id="UniqueNotationName" diff="add"><head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E22">[E22]</loc>Unique +Notation Name</head><p>Only one notation declaration can declare a given <nt +def="NT-Name">Name</nt>.</p> +</vcnote> +<p>XML processors must provide applications with the name and external identifier(s) +of any notation declared and referred to in an attribute value, attribute +definition, or entity declaration. They may additionally resolve the external +identifier into the <termref def="dt-sysid">system identifier</termref>, file +name, or other information needed to allow the application to call a processor +for data in the notation described. (It is not an error, however, for XML +documents to declare and refer to notations for which notation-specific applications +are not available on the system where the XML processor or application is +running.)</p> +</div2> +<div2 id="sec-doc-entity"> +<head>Document Entity</head> +<p><termdef id="dt-docent" term="Document Entity">The <term>document entity</term> +serves as the root of the entity tree and a starting-point for an <termref +def="dt-xml-proc">XML processor</termref>.</termdef> This specification does +not specify how the document entity is to be located by an XML processor; +unlike other entities, the document entity has no name and might well appear +on a processor input stream without any identification at all.</p> +</div2> +</div1> +<!-- &Conformance; --> +<div1 id="sec-conformance"> +<head>Conformance</head> +<div2 id="proc-types"> +<head>Validating and Non-Validating Processors</head> +<p>Conforming <termref def="dt-xml-proc">XML processors</termref> fall into +two classes: validating and non-validating.</p> +<p>Validating and non-validating processors alike must report violations of +this specification's well-formedness constraints in the content of the <termref +def="dt-docent">document entity</termref> and any other <termref def="dt-parsedent">parsed +entities</termref> that they read.</p> +<p><termdef id="dt-validating" term="Validating Processor"><term>Validating +processors</term> must<phrase diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E21">[E21]</loc>, +at user option,</phrase> report violations of the constraints expressed by +the declarations in the <termref def="dt-doctype">DTD</termref>, and failures +to fulfill the validity constraints given in this specification.</termdef> +To accomplish this, validating XML processors must read and process the entire +DTD and all external parsed entities referenced in the document.</p> +<p>Non-validating processors are required to check only the <termref def="dt-docent">document +entity</termref>, including the entire internal DTD subset, for well-formedness. <termdef +id="dt-use-mdecl" term="Process Declarations"> While they are not required +to check the document for validity, they are required to <term>process</term> +all the declarations they read in the internal DTD subset and in any parameter +entity that they read, up to the first reference to a parameter entity that +they do <emph>not</emph> read; that is to say, they must use the information +in those declarations to <titleref href="#AVNormalize">normalize</titleref> +attribute values, <titleref href="#included">include</titleref> the replacement +text of internal entities, and supply <titleref href="#sec-attr-defaults">default +attribute values</titleref>.</termdef> <phrase diff="add"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E33">[E33]</loc>Except when <code>standalone="yes"</code>, </phrase>they +must not <termref def="dt-use-mdecl">process</termref> <termref def="dt-entdecl">entity +declarations</termref> or <termref def="dt-attdecl">attribute-list declarations</termref> +encountered after a reference to a parameter entity that is not read, since +the entity may have contained overriding declarations.</p> +</div2> +<div2 id="safe-behavior"> +<head>Using XML Processors</head> +<p>The behavior of a validating XML processor is highly predictable; it must +read every piece of a document and report all well-formedness and validity +violations. Less is required of a non-validating processor; it need not read +any part of the document other than the document entity. This has two effects +that may be important to users of XML processors:</p> +<ulist> +<item><p>Certain well-formedness errors, specifically those that require reading +external entities, may not be detected by a non-validating processor. Examples +include the constraints entitled <titleref href="#wf-entdeclared">Entity Declared</titleref>, <titleref +href="#textent">Parsed Entity</titleref>, and <titleref href="#norecursion">No +Recursion</titleref>, as well as some of the cases described as <titleref +href="#forbidden">forbidden</titleref> in <specref ref="entproc"/>.</p></item> +<item><p>The information passed from the processor to the application may +vary, depending on whether the processor reads parameter and external entities. +For example, a non-validating processor may not <titleref href="#AVNormalize">normalize</titleref> +attribute values, <titleref href="#included">include</titleref> the replacement +text of internal entities, or supply <titleref href="#sec-attr-defaults">default +attribute values</titleref>, where doing so depends on having read declarations +in external or parameter entities.</p></item> +</ulist> +<p>For maximum reliability in interoperating between different XML processors, +applications which use non-validating processors should not rely on any behaviors +not required of such processors. Applications which require facilities such +as the use of default attributes or internal entities which are declared in +external entities should use validating XML processors.</p> +</div2> +</div1> +<div1 id="sec-notation"> +<head>Notation</head> +<p>The formal grammar of XML is given in this specification using a simple +Extended Backus-Naur Form (EBNF) notation. Each rule in the grammar defines +one symbol, in the form</p> +<eg>symbol ::= expression</eg> +<p>Symbols are written with an initial capital letter if they are <phrase +diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E42">[E42]</loc>the +start symbol of a regular language,</phrase> otherwise with an initial lower +case letter. Literal strings are quoted.</p> +<p>Within the expression on the right-hand side of a rule, the following expressions +are used to match strings of one or more characters: <glist> +<gitem><label><code>#xN</code></label> +<def> +<p>where <code>N</code> is a hexadecimal integer, the expression matches the +character in ISO/IEC 10646 whose canonical (UCS-4) code value, when interpreted +as an unsigned binary number, has the value indicated. The number of leading +zeros in the <code>#xN</code> form is insignificant; the number of leading +zeros in the corresponding code value is governed by the character encoding +in use and is not significant for XML.</p> +</def></gitem> +<gitem><label><code>[a-zA-Z]</code>, <code>[#xN-#xN]</code></label> +<def> +<p>matches any <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E93">[E93]</loc><nt +def="NT-Char">Char</nt></phrase> with a value in the range(s) indicated (inclusive).</p> +</def></gitem> +<gitem diff="add"><label><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E3">[E3]</loc><code>[abc]</code>, <code>[#xN#xN#xN]</code +></label> +<def> +<p>matches any <nt def="NT-Char">Char</nt> with a value among the characters +enumerated. Enumerations and ranges can be mixed in one set of brackets.</p> +</def></gitem> +<gitem><label><code>[^a-z]</code>, <code>[^#xN-#xN]</code></label> +<def> +<p>matches any <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E93">[E93]</loc><nt +def="NT-Char">Char</nt></phrase> with a value <emph>outside</emph> the range +indicated.</p> +</def></gitem> +<gitem><label><code>[^abc]</code>, <code>[^#xN#xN#xN]</code></label> +<def> +<p>matches any <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E93">[E93]</loc><nt +def="NT-Char">Char</nt></phrase> with a value not among the characters given. <phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E3">[E3]</loc>Enumerations +and ranges of forbidden values can be mixed in one set of brackets.</phrase></p> +</def></gitem> +<gitem><label><code>"string"</code></label> +<def> +<p>matches a literal string <termref def="dt-match">matching</termref> that +given inside the double quotes.</p> +</def></gitem> +<gitem><label><code>'string'</code></label> +<def> +<p>matches a literal string <termref def="dt-match">matching</termref> that +given inside the single quotes.</p> +</def></gitem> +</glist> These symbols may be combined to match more complex patterns as follows, +where <code>A</code> and <code>B</code> represent simple expressions: <glist> +<gitem><label>(<code>expression</code>)</label> +<def> +<p><code>expression</code> is treated as a unit and may be combined as described +in this list.</p> +</def></gitem> +<gitem><label><code>A?</code></label> +<def> +<p>matches <code>A</code> or nothing; optional <code>A</code>.</p> +</def></gitem> +<gitem><label><code>A B</code></label> +<def> +<p>matches <code>A</code> followed by <code>B</code>. <phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E20">[E20]</loc>This +operator has higher precedence than alternation; thus <code>A B | C D</code> +is identical to <code>(A B) | (C D)</code>.</phrase></p> +</def></gitem> +<gitem><label><code>A | B</code></label> +<def> +<p>matches <code>A</code> or <code>B</code> but not both.</p> +</def></gitem> +<gitem><label><code>A - B</code></label> +<def> +<p>matches any string that matches <code>A</code> but does not match <code>B</code>.</p> +</def></gitem> +<gitem><label><code>A+</code></label> +<def> +<p>matches one or more occurrences of <code>A</code>.<phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E20">[E20]</loc>Concatenation +has higher precedence than alternation; thus <code>A+ | B+</code> is identical +to <code>(A+) | (B+)</code>.</phrase></p> +</def></gitem> +<gitem><label><code>A*</code></label> +<def> +<p>matches zero or more occurrences of <code>A</code>. <phrase diff="add"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E20">[E20]</loc>Concatenation +has higher precedence than alternation; thus <code>A* | B*</code> is identical +to <code>(A*) | (B*)</code>.</phrase></p> +</def></gitem> +</glist> Other notations used in the productions are: <glist> +<gitem><label><code>/* ... */</code></label> +<def> +<p>comment.</p> +</def></gitem> +<gitem><label><code>[ wfc: ... ]</code></label> +<def> +<p>well-formedness constraint; this identifies by name a constraint on <termref +def="dt-wellformed">well-formed</termref> documents associated with a production.</p> +</def></gitem> +<gitem><label><code>[ vc: ... ]</code></label> +<def> +<p>validity constraint; this identifies by name a constraint on <termref def="dt-valid">valid</termref> +documents associated with a production.</p> +</def></gitem> +</glist></p> +</div1> +</body><back> +<!-- &SGML; --> +<!-- &Biblio; --> +<div1 id="sec-bibliography"> +<head>References</head> +<div2 id="sec-existing-stds"> +<head>Normative References</head> +<blist> +<bibl id="IANA" diff="chg" key="IANA-CHARSETS"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</loc>(Internet +Assigned Numbers Authority) <titleref>Official Names for Character Sets</titleref>, +ed. Keld Simonsen et al. See <loc href="ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets">ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets</loc +>. </bibl> +<bibl id="RFC1766" href="http://www.ietf.org/rfc/rfc1766.txt" key="IETF RFC 1766">IETF +(Internet Engineering Task Force). <titleref>RFC 1766: Tags for the Identification +of Languages</titleref>, ed. H. Alvestrand. 1995.</bibl> +<bibl id="ISO639-old" diff="del" key="ISO 639"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</loc> +(International Organization for Standardization). <titleref>ISO 639:1988 (E). +Code for the representation of names of languages.</titleref> [Geneva]: International +Organization for Standardization, 1988.</bibl> +<bibl id="ISO3166-old" diff="del" key="ISO 3166"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</loc> +(International Organization for Standardization). <titleref>ISO 3166-1:1997 +(E). Codes for the representation of names of countries and their subdivisions — +Part 1: Country codes</titleref> [Geneva]: International Organization for +Standardization, 1997.</bibl> +<bibl id="ISO10646" key="ISO/IEC 10646">ISO (International Organization for +Standardization). <titleref>ISO/IEC 10646-1993 (E). Information technology — +Universal Multiple-Octet Coded Character Set (UCS) — Part 1: Architecture +and Basic Multilingual Plane.</titleref> [Geneva]: International Organization +for Standardization, 1993 (plus amendments AM 1 through AM 7).</bibl> +<bibl id="ISO10646-2000" diff="add" key="ISO/IEC 10646-2000"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc> ISO (International +Organization for Standardization). <titleref>ISO/IEC 10646-1:2000. Information +technology — Universal Multiple-Octet Coded Character Set (UCS) — +Part 1: Architecture and Basic Multilingual Plane.</titleref> [Geneva]: International +Organization for Standardization, 2000.</bibl> +<bibl id="Unicode" key="Unicode">The Unicode Consortium. <emph>The Unicode +Standard, Version 2.0.</emph> Reading, Mass.: Addison-Wesley Developers Press, +1996.</bibl> +<bibl id="Unicode3" diff="add" key="Unicode3"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc> +The Unicode Consortium. <emph>The Unicode Standard, Version 3.0.</emph> Reading, +Mass.: Addison-Wesley Developers Press, 2000. ISBN 0-201-61633-5.</bibl> +</blist></div2> +<div2 id="null"> +<!-- +ID made "null" to match its previous value in the First +Edition; it's odd, but if there's no set value, the stylesheet +currently generates an odd string that would be backwards +incompatible with any references anyone might have made before. +--> +<head>Other References</head> +<blist> +<bibl id="Aho" key="Aho/Ullman">Aho, Alfred V., Ravi Sethi, and Jeffrey D. +Ullman. <titleref>Compilers: Principles, Techniques, and Tools</titleref>. +Reading: Addison-Wesley, 1986, rpt. corr. 1988.</bibl> +<bibl id="Berners-Lee" key="Berners-Lee et al."> Berners-Lee, T., R. Fielding, +and L. Masinter. <titleref>Uniform Resource Identifiers (URI): Generic Syntax +and Semantics</titleref>. 1997. (Work in progress; see updates to RFC1738.)</bibl> +<bibl id="ABK" diff="chg" key="Brüggemann-Klein"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E2">[E2]</loc>Brüggemann-Klein, +Anne. Formal Models in Document Processing. Habilitationsschrift. Faculty +of Mathematics at the University of Freiburg, 1993. (See <loc href="ftp://ftp.informatik.uni-freiburg.de/documents/papers/brueggem/habil.ps">ftp://ftp.informatik.uni-freiburg.de/documents/papers/brueggem/habil.ps</loc +>.)</bibl> +<bibl id="ABKDW" diff="chg" key="Brüggemann-Klein and Wood"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E2">[E2]</loc>Brüggemann-Klein, +Anne, and Derick Wood. <titleref>Deterministic Regular Languages</titleref>. +Universität Freiburg, Institut für Informatik, Bericht 38, Oktober 1991. Extended +abstract in A. Finkel, M. Jantzen, Hrsg., STACS 1992, S. 173-184. Springer-Verlag, +Berlin 1992. Lecture Notes in Computer Science 577. Full version titled <titleref>One-Unambiguous +Regular Languages</titleref> in Information and Computation 140 (2): 229-253, +February 1998.</bibl> +<bibl id="Clark" key="Clark">James Clark. Comparison of SGML and XML. See <loc +href="http://www.w3.org/TR/NOTE-sgml-xml-971215">http://www.w3.org/TR/NOTE-sgml-xml-971215</loc>. </bibl> +<bibl id="IANA-LANGCODES" diff="add" href="http://www.isi.edu/in-notes/iana/assignments/languages/" +key="IANA-LANGCODES"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</loc>(Internet +Assigned Numbers Authority) <titleref>Registry of Language Tags</titleref>, +ed. Keld Simonsen et al.</bibl> +<bibl id="RFC1738" diff="del" href="http://www.ietf.org/rfc/rfc1738.txt" key="IETF RFC1738">IETF +(Internet Engineering Task Force). <titleref>RFC 1738: Uniform Resource Locators +(URL)</titleref>, ed. T. Berners-Lee, L. Masinter, M. McCahill. 1994. </bibl> +<bibl id="RFC1808" diff="del" href="http://www.ietf.org/rfc/rfc1808.txt" key="IETF RFC1808">IETF +(Internet Engineering Task Force). <titleref>RFC 1808: Relative Uniform Resource +Locators</titleref>, ed. R. Fielding. 1995. </bibl> +<bibl id="RFC2141" href="http://www.ietf.org/rfc/rfc2141.txt" key="IETF RFC2141">IETF +(Internet Engineering Task Force). <emph>RFC 2141: URN Syntax</emph>, ed. +R. Moats. 1997. </bibl> +<bibl id="rfc2279" diff="add" href="http://www.ietf.org/rfc/rfc2279.txt" key="IETF RFC 2279"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E78">[E78]</loc>IETF +(Internet Engineering Task Force). <titleref>RFC 2279: UTF-8, a transformation +format of ISO 10646</titleref>, <phrase diff="add">ed. F. Yergeau, </phrase>1998.</bibl> +<bibl id="rfc2376" diff="add" href="http://www.ietf.org/rfc/rfc2376.txt" key="IETF RFC 2376"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E48">[E48]</loc>IETF +(Internet Engineering Task Force). <titleref>RFC 2376: XML Media Types</titleref>. +ed. E. Whitehead, M. Murata. 1998.</bibl> +<bibl id="rfc2396" diff="add" href="http://www.ietf.org/rfc/rfc2396.txt" key="IETF RFC 2396"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</loc>IETF +(Internet Engineering Task Force). <titleref>RFC 2396: Uniform Resource Identifiers +(URI): Generic Syntax</titleref>. T. Berners-Lee, R. Fielding, L. Masinter. +1998.</bibl> +<bibl id="rfc2732" diff="add" href="http://www.ietf.org/rfc/rfc2732.txt" key="IETF RFC 2732"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</loc>IETF +(Internet Engineering Task Force). <titleref>RFC 2732: Format for Literal +IPv6 Addresses in URL's</titleref>. R. Hinden, B. Carpenter, L. Masinter. +1999.</bibl> +<bibl id="rfc2781" diff="add" href="http://www.ietf.org/rfc/rfc2781.txt" key="IETF RFC 2781"><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E77">[E77]</loc> +IETF (Internet Engineering Task Force). <emph>RFC 2781: UTF-16, an encoding +of ISO 10646</emph>, ed. P. Hoffman, F. Yergeau. 2000.</bibl> +<bibl id="ISO639" diff="add" key="ISO 639"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</loc> +(International Organization for Standardization). <titleref>ISO 639:1988 (E). +Code for the representation of names of languages.</titleref> [Geneva]: International +Organization for Standardization, 1988.</bibl> +<bibl id="ISO3166" diff="add" key="ISO 3166"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</loc> +(International Organization for Standardization). <titleref>ISO 3166-1:1997 +(E). Codes for the representation of names of countries and their subdivisions — +Part 1: Country codes</titleref> [Geneva]: International Organization for +Standardization, 1997.</bibl> +<bibl id="ISO8879" key="ISO 8879">ISO (International Organization for Standardization). <titleref>ISO +8879:1986(E). Information processing — Text and Office Systems — +Standard Generalized Markup Language (SGML).</titleref> First edition — +1986-10-15. [Geneva]: International Organization for Standardization, 1986. </bibl> +<bibl id="ISO10744" key="ISO/IEC 10744">ISO (International Organization for +Standardization). <titleref>ISO/IEC 10744-1992 (E). Information technology — +Hypermedia/Time-based Structuring Language (HyTime). </titleref> [Geneva]: +International Organization for Standardization, 1992. <emph>Extended Facilities +Annexe.</emph> [Geneva]: International Organization for Standardization, 1996. </bibl> +<bibl id="websgml" diff="add" href="http://www.sgmlsource.com/8879rev/n0029.htm" +key="WEBSGML"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E43">[E43]</loc>ISO +(International Organization for Standardization). <titleref>ISO 8879:1986 +TC2. Information technology — Document Description and Processing Languages. </titleref> +[Geneva]: International Organization for Standardization, 1998.</bibl> +<bibl id="xml-names" diff="add" xmlns:xlink="http://www.w3.org/TR/WD-xlink" +href="http://www.w3.org/TR/REC-xml-names/" key="XML Names"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E98">[E98]</loc>Tim Bray, +Dave Hollander, and Andrew Layman, editors. <titleref>Namespaces in XML</titleref>. +Textuality, Hewlett-Packard, and Microsoft. World Wide Web Consortium, 1999.</bibl> +</blist></div2> +</div1> +<div1 id="CharClasses"> +<head>Character Classes</head> +<p>Following the characteristics defined in the Unicode standard, characters +are classed as base characters (among others, these contain the alphabetic +characters of the Latin alphabet<phrase diff="del"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E84">[E84]</loc>, without +diacritics</phrase>), ideographic characters, and combining characters (among +others, this class contains most diacritics)<phrase diff="del"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E30">[E30]</loc>; these classes +combine to form the class of letters.</phrase> Digits and extenders are also +distinguished.</p> +<scrap id="CHARACTERS" lang="ebnf"> +<head>Characters</head> +<prodgroup pcw3="3" pcw4="15"> +<prod id="NT-Letter"> +<lhs>Letter</lhs><rhs><nt def="NT-BaseChar">BaseChar</nt> | <nt def="NT-Ideographic">Ideographic</nt></rhs> +</prod> +<prod id="NT-BaseChar"> +<lhs>BaseChar</lhs><rhs>[#x0041-#x005A] | [#x0061-#x007A] | [#x00C0-#x00D6] +| [#x00D8-#x00F6] | [#x00F8-#x00FF] | [#x0100-#x0131] | [#x0134-#x013E] +| [#x0141-#x0148] | [#x014A-#x017E] | [#x0180-#x01C3] | [#x01CD-#x01F0] +| [#x01F4-#x01F5] | [#x01FA-#x0217] | [#x0250-#x02A8] | [#x02BB-#x02C1] +| #x0386 | [#x0388-#x038A] | #x038C | [#x038E-#x03A1] +| [#x03A3-#x03CE] | [#x03D0-#x03D6] | #x03DA | #x03DC +| #x03DE | #x03E0 | [#x03E2-#x03F3] | [#x0401-#x040C] +| [#x040E-#x044F] | [#x0451-#x045C] | [#x045E-#x0481] | [#x0490-#x04C4] +| [#x04C7-#x04C8] | [#x04CB-#x04CC] | [#x04D0-#x04EB] | [#x04EE-#x04F5] +| [#x04F8-#x04F9] | [#x0531-#x0556] | #x0559 | [#x0561-#x0586] +| [#x05D0-#x05EA] | [#x05F0-#x05F2] | [#x0621-#x063A] | [#x0641-#x064A] +| [#x0671-#x06B7] | [#x06BA-#x06BE] | [#x06C0-#x06CE] | [#x06D0-#x06D3] +| #x06D5 | [#x06E5-#x06E6] | [#x0905-#x0939] | #x093D +| [#x0958-#x0961] | [#x0985-#x098C] | [#x098F-#x0990] | [#x0993-#x09A8] +| [#x09AA-#x09B0] | #x09B2 | [#x09B6-#x09B9] | [#x09DC-#x09DD] +| [#x09DF-#x09E1] | [#x09F0-#x09F1] | [#x0A05-#x0A0A] | [#x0A0F-#x0A10] +| [#x0A13-#x0A28] | [#x0A2A-#x0A30] | [#x0A32-#x0A33] | [#x0A35-#x0A36] +| [#x0A38-#x0A39] | [#x0A59-#x0A5C] | #x0A5E | [#x0A72-#x0A74] +| [#x0A85-#x0A8B] | #x0A8D | [#x0A8F-#x0A91] | [#x0A93-#x0AA8] +| [#x0AAA-#x0AB0] | [#x0AB2-#x0AB3] | [#x0AB5-#x0AB9] | #x0ABD +| #x0AE0 | [#x0B05-#x0B0C] | [#x0B0F-#x0B10] | [#x0B13-#x0B28] +| [#x0B2A-#x0B30] | [#x0B32-#x0B33] | [#x0B36-#x0B39] | #x0B3D +| [#x0B5C-#x0B5D] | [#x0B5F-#x0B61] | [#x0B85-#x0B8A] | [#x0B8E-#x0B90] +| [#x0B92-#x0B95] | [#x0B99-#x0B9A] | #x0B9C | [#x0B9E-#x0B9F] +| [#x0BA3-#x0BA4] | [#x0BA8-#x0BAA] | [#x0BAE-#x0BB5] | [#x0BB7-#x0BB9] +| [#x0C05-#x0C0C] | [#x0C0E-#x0C10] | [#x0C12-#x0C28] | [#x0C2A-#x0C33] +| [#x0C35-#x0C39] | [#x0C60-#x0C61] | [#x0C85-#x0C8C] | [#x0C8E-#x0C90] +| [#x0C92-#x0CA8] | [#x0CAA-#x0CB3] | [#x0CB5-#x0CB9] | #x0CDE +| [#x0CE0-#x0CE1] | [#x0D05-#x0D0C] | [#x0D0E-#x0D10] | [#x0D12-#x0D28] +| [#x0D2A-#x0D39] | [#x0D60-#x0D61] | [#x0E01-#x0E2E] | #x0E30 +| [#x0E32-#x0E33] | [#x0E40-#x0E45] | [#x0E81-#x0E82] | #x0E84 +| [#x0E87-#x0E88] | #x0E8A | #x0E8D | [#x0E94-#x0E97] +| [#x0E99-#x0E9F] | [#x0EA1-#x0EA3] | #x0EA5 | #x0EA7 +| [#x0EAA-#x0EAB] | [#x0EAD-#x0EAE] | #x0EB0 | [#x0EB2-#x0EB3] +| #x0EBD | [#x0EC0-#x0EC4] | [#x0F40-#x0F47] | [#x0F49-#x0F69] +| [#x10A0-#x10C5] | [#x10D0-#x10F6] | #x1100 | [#x1102-#x1103] +| [#x1105-#x1107] | #x1109 | [#x110B-#x110C] | [#x110E-#x1112] +| #x113C | #x113E | #x1140 | #x114C | #x114E | #x1150 +| [#x1154-#x1155] | #x1159 | [#x115F-#x1161] | #x1163 +| #x1165 | #x1167 | #x1169 | [#x116D-#x116E] | [#x1172-#x1173] +| #x1175 | #x119E | #x11A8 | #x11AB | [#x11AE-#x11AF] +| [#x11B7-#x11B8] | #x11BA | [#x11BC-#x11C2] | #x11EB +| #x11F0 | #x11F9 | [#x1E00-#x1E9B] | [#x1EA0-#x1EF9] +| [#x1F00-#x1F15] | [#x1F18-#x1F1D] | [#x1F20-#x1F45] | [#x1F48-#x1F4D] +| [#x1F50-#x1F57] | #x1F59 | #x1F5B | #x1F5D | [#x1F5F-#x1F7D] +| [#x1F80-#x1FB4] | [#x1FB6-#x1FBC] | #x1FBE | [#x1FC2-#x1FC4] +| [#x1FC6-#x1FCC] | [#x1FD0-#x1FD3] | [#x1FD6-#x1FDB] | [#x1FE0-#x1FEC] +| [#x1FF2-#x1FF4] | [#x1FF6-#x1FFC] | #x2126 | [#x212A-#x212B] +| #x212E | [#x2180-#x2182] | [#x3041-#x3094] | [#x30A1-#x30FA] +| [#x3105-#x312C] | [#xAC00-#xD7A3] </rhs> +</prod> +<prod id="NT-Ideographic"> +<lhs>Ideographic</lhs><rhs>[#x4E00-#x9FA5] | #x3007 | [#x3021-#x3029] </rhs> +</prod> +<prod id="NT-CombiningChar"> +<lhs>CombiningChar</lhs><rhs>[#x0300-#x0345] | [#x0360-#x0361] | [#x0483-#x0486] +| [#x0591-#x05A1] | [#x05A3-#x05B9] | [#x05BB-#x05BD] | #x05BF +| [#x05C1-#x05C2] | #x05C4 | [#x064B-#x0652] | #x0670 +| [#x06D6-#x06DC] | [#x06DD-#x06DF] | [#x06E0-#x06E4] | [#x06E7-#x06E8] +| [#x06EA-#x06ED] | [#x0901-#x0903] | #x093C | [#x093E-#x094C] +| #x094D | [#x0951-#x0954] | [#x0962-#x0963] | [#x0981-#x0983] +| #x09BC | #x09BE | #x09BF | [#x09C0-#x09C4] | [#x09C7-#x09C8] +| [#x09CB-#x09CD] | #x09D7 | [#x09E2-#x09E3] | #x0A02 +| #x0A3C | #x0A3E | #x0A3F | [#x0A40-#x0A42] | [#x0A47-#x0A48] +| [#x0A4B-#x0A4D] | [#x0A70-#x0A71] | [#x0A81-#x0A83] | #x0ABC +| [#x0ABE-#x0AC5] | [#x0AC7-#x0AC9] | [#x0ACB-#x0ACD] | [#x0B01-#x0B03] +| #x0B3C | [#x0B3E-#x0B43] | [#x0B47-#x0B48] | [#x0B4B-#x0B4D] +| [#x0B56-#x0B57] | [#x0B82-#x0B83] | [#x0BBE-#x0BC2] | [#x0BC6-#x0BC8] +| [#x0BCA-#x0BCD] | #x0BD7 | [#x0C01-#x0C03] | [#x0C3E-#x0C44] +| [#x0C46-#x0C48] | [#x0C4A-#x0C4D] | [#x0C55-#x0C56] | [#x0C82-#x0C83] +| [#x0CBE-#x0CC4] | [#x0CC6-#x0CC8] | [#x0CCA-#x0CCD] | [#x0CD5-#x0CD6] +| [#x0D02-#x0D03] | [#x0D3E-#x0D43] | [#x0D46-#x0D48] | [#x0D4A-#x0D4D] +| #x0D57 | #x0E31 | [#x0E34-#x0E3A] | [#x0E47-#x0E4E] +| #x0EB1 | [#x0EB4-#x0EB9] | [#x0EBB-#x0EBC] | [#x0EC8-#x0ECD] +| [#x0F18-#x0F19] | #x0F35 | #x0F37 | #x0F39 | #x0F3E +| #x0F3F | [#x0F71-#x0F84] | [#x0F86-#x0F8B] | [#x0F90-#x0F95] +| #x0F97 | [#x0F99-#x0FAD] | [#x0FB1-#x0FB7] | #x0FB9 +| [#x20D0-#x20DC] | #x20E1 | [#x302A-#x302F] | #x3099 +| #x309A </rhs> +</prod> +<prod id="NT-Digit"> +<lhs>Digit</lhs><rhs>[#x0030-#x0039] | [#x0660-#x0669] | [#x06F0-#x06F9] +| [#x0966-#x096F] | [#x09E6-#x09EF] | [#x0A66-#x0A6F] | [#x0AE6-#x0AEF] +| [#x0B66-#x0B6F] | [#x0BE7-#x0BEF] | [#x0C66-#x0C6F] | [#x0CE6-#x0CEF] +| [#x0D66-#x0D6F] | [#x0E50-#x0E59] | [#x0ED0-#x0ED9] | [#x0F20-#x0F29] </rhs> +</prod> +<prod id="NT-Extender"> +<lhs>Extender</lhs><rhs>#x00B7 | #x02D0 | #x02D1 | #x0387 | #x0640 +| #x0E46 | #x0EC6 | #x3005 | [#x3031-#x3035] | [#x309D-#x309E] +| [#x30FC-#x30FE] </rhs> +</prod> +</prodgroup></scrap> +<p>The character classes defined here can be derived from the Unicode <phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc>2.0</phrase> +character database as follows:</p> +<ulist> +<item><p>Name start characters must have one of the categories Ll, Lu, Lo, +Lt, Nl.</p></item> +<item><p>Name characters other than Name-start characters must have one of +the categories Mc, Me, Mn, Lm, or Nd.</p></item> +<item><p>Characters in the compatibility area (i.e. with character code greater +than #xF900 and less than #xFFFE) are not allowed in XML names.</p></item> +<item><p>Characters which have a font or compatibility decomposition (i.e. +those with a <quote>compatibility formatting tag</quote> in field 5 of the +database -- marked by field 5 beginning with a <quote><</quote>) are not +allowed.</p></item> +<item><p>The following characters are treated as name-start characters rather +than name characters, because the property file classifies them as Alphabetic: +[#x02BB-#x02C1], #x0559, #x06E5, #x06E6.</p></item> +<item><p>Characters #x20DD-#x20E0 are excluded (in accordance with Unicode <phrase +diff="add"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</loc>2.0</phrase>, +section 5.14).</p></item> +<item><p>Character #x00B7 is classified as an extender, because the property +list so identifies it.</p></item> +<item><p>Character #x0387 is added as a name character, because #x00B7 is +its canonical equivalent.</p></item> +<item><p>Characters ':' and '_' are allowed as name-start characters.</p> +</item> +<item><p>Characters '-' and '.' are allowed as name characters.</p></item> +</ulist> +</div1> +<inform-div1 id="sec-xml-and-sgml"> +<head>XML and SGML</head> +<p><phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E43">[E43]</loc>XML +is designed to be a subset of SGML, in that every XML document should also +be a conforming SGML document.</phrase> For a detailed comparison of the additional +restrictions that XML places on documents beyond those of SGML, see <bibref +ref="Clark"/>.</p> +</inform-div1> +<inform-div1 id="sec-entexpand"> +<head>Expansion of Entity and Character References</head> +<p>This appendix contains some examples illustrating the sequence of entity- +and character-reference recognition and expansion, as specified in <specref +ref="entproc"/>.</p> +<p>If the DTD contains the declaration</p> +<eg><![CDATA[<!ENTITY example "<p>An ampersand (&#38;) may be escaped +numerically (&#38;#38;) or with a general entity +(&amp;).</p>" >]]></eg> +<p>then the XML processor will recognize the character references when it +parses the entity declaration, and resolve them before storing the following +string as the value of the entity <quote><code>example</code></quote>:</p> +<eg><![CDATA[<p>An ampersand (&) may be escaped +numerically (&#38;) or with a general entity +(&amp;).</p>]]></eg> +<p>A reference in the document to <quote><code>&example;</code></quote> +will cause the text to be reparsed, at which time the start- and end-tags +of the <el>p</el> element will be recognized and the three references will +be recognized and expanded, resulting in a <el>p</el> element with the following +content (all data, no delimiters or markup):</p> +<eg><![CDATA[An ampersand (&) may be escaped +numerically (&) or with a general entity +(&).]]></eg> +<p>A more complex example will illustrate the rules and their effects fully. +In the following example, the line numbers are solely for reference.</p> +<eg><![CDATA[1 <?xml version='1.0'?> +2 <!DOCTYPE test [ +3 <!ELEMENT test (#PCDATA) > +4 <!ENTITY % xx '%zz;'> +5 <!ENTITY % zz '<!ENTITY tricky "error-prone" >' > +6 %xx; +7 ]> +8 <test>This sample shows a &tricky; method.</test>]]></eg> +<p>This produces the following:</p> +<ulist spacing="compact"> +<item><p>in line 4, the reference to character 37 is expanded immediately, +and the parameter entity <quote><code>xx</code></quote> is stored in the symbol +table with the value <quote><code>%zz;</code></quote>. Since the replacement +text is not rescanned, the reference to parameter entity <quote><code>zz</code></quote> +is not recognized. (And it would be an error if it were, since <quote><code>zz</code></quote> +is not yet declared.)</p></item> +<item><p>in line 5, the character reference <quote><code>&#60;</code></quote> +is expanded immediately and the parameter entity <quote><code>zz</code></quote> +is stored with the replacement text <quote><code><!ENTITY tricky "error-prone" +></code></quote>, which is a well-formed entity declaration.</p></item> +<item><p>in line 6, the reference to <quote><code>xx</code></quote> is recognized, +and the replacement text of <quote><code>xx</code></quote> (namely <quote><code>%zz;</code></quote>) +is parsed. The reference to <quote><code>zz</code></quote> is recognized in +its turn, and its replacement text (<quote><code><!ENTITY tricky "error-prone" +></code></quote>) is parsed. The general entity <quote><code>tricky</code></quote> +has now been declared, with the replacement text <quote><code>error-prone</code></quote>.</p> +</item> +<item><p>in line 8, the reference to the general entity <quote><code>tricky</code></quote> +is recognized, and it is expanded, so the full content of the <el>test</el> +element is the self-describing (and ungrammatical) string <emph>This sample +shows a error-prone method.</emph></p></item> +</ulist> +</inform-div1> +<inform-div1 id="determinism"> +<head>Deterministic Content Models</head> +<p><phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E102">[E102]</loc>As +noted in <specref ref="sec-element-content"/>, it is required that content +models in element type declarations be deterministic. This requirement is <termref +def="dt-compat">for compatibility</termref> with SGML (which calls deterministic +content models <quote>unambiguous</quote>);</phrase> XML processors built +using SGML systems may flag non-deterministic content models as errors.</p> +<p>For example, the content model <code>((b, c) | (b, d))</code> is non-deterministic, +because given an initial <el>b</el> the <phrase diff="chg"><loc role="erratumref" +href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</loc>XML processor</phrase> +cannot know which <el>b</el> in the model is being matched without looking +ahead to see which element follows the <el>b</el>. In this case, the two references +to <el>b</el> can be collapsed into a single reference, making the model read <code>(b, +(c | d))</code>. An initial <el>b</el> now clearly matches only a single name +in the content model. The <phrase diff="chg"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</loc>processor</phrase +> doesn't need to look ahead to see what follows; either <el>c</el> or <el>d</el> +would be accepted.</p> +<p>More formally: a finite state automaton may be constructed from the content +model using the standard algorithms, e.g. algorithm 3.5 in section 3.9 of +Aho, Sethi, and Ullman <bibref ref="Aho"/>. In many such algorithms, a follow +set is constructed for each position in the regular expression (i.e., each +leaf node in the syntax tree for the regular expression); if any position +has a follow set in which more than one following position is labeled with +the same element type name, then the content model is in error and may be +reported as an error.</p> +<p>Algorithms exist which allow many but not all non-deterministic content +models to be reduced automatically to equivalent deterministic models; see +Brüggemann-Klein 1991 <bibref ref="ABK"/>.</p> +</inform-div1> +<inform-div1 id="sec-guessing"> +<head><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E105">[E105]</loc><loc +role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E48">[E48]</loc>Autodetection +of Character Encodings</head> +<p>The XML encoding declaration functions as an internal label on each entity, +indicating which character encoding is in use. Before an XML processor can +read the internal label, however, it apparently has to know what character +encoding is in use—which is what the internal label is trying to indicate. +In the general case, this is a hopeless situation. It is not entirely hopeless +in XML, however, because XML limits the general case in two ways: each implementation +is assumed to support only a finite set of character encodings, and the XML +encoding declaration is restricted in position and content in order to make +it feasible to autodetect the character encoding in use in each entity in +normal cases. Also, in many cases other sources of information are available +in addition to the XML data stream itself. Two cases may be distinguished, +depending on whether the XML entity is presented to the processor without, +or with, any accompanying (external) information. We consider the first case +first.</p> +<div2 id="sec-guessing-no-ext-info"> +<head diff="add">Detection Without External Encoding Information</head> +<p>Because each XML entity <phrase diff="add">not accompanied by external +encoding information and </phrase>not in UTF-8 or UTF-16 <phrase diff="chg">encoding</phrase> <emph>must</emph> +begin with an XML encoding declaration, in which the first characters must +be '<code><?xml</code>', any conforming processor can detect, after two +to four octets of input, which of the following cases apply. In reading this +list, it may help to know that in UCS-4, '<' is <quote><code>#x0000003C</code></quote> +and '?' is <quote><code>#x0000003F</code></quote>, and the Byte Order Mark +required of UTF-16 data streams is <quote><code>#xFEFF</code></quote>. <phrase +diff="add">The notation <var>##</var> is used to denote any byte value except <phrase +diff="chg">that two consecutive <var>##</var>s cannot be both 00</phrase>.</phrase></p> +<p diff="add">With a Byte Order Mark:</p> +<table diff="add" border="1" frame="border"><tbody><tr><td><code>00 00 FE +FF</code></td><td>UCS-4, big-endian machine (1234 order)</td></tr><tr><td><code>FF +FE 00 00</code></td><td>UCS-4, little-endian machine (4321 order)</td></tr> +<tr><td><code>00 00 FF FE</code></td><td>UCS-4, unusual octet order (2143)</td> +</tr><tr><td><code>FE FF 00 00</code></td><td>UCS-4, unusual octet order (3412)</td> +</tr><tr><td><code>FE FF ## ##</code></td><td>UTF-16, big-endian</td></tr> +<tr><td><code>FF FE ## ##</code></td><td>UTF-16, little-endian</td></tr><tr> +<td><code>EF BB BF</code></td><td>UTF-8</td></tr></tbody></table> +<p diff="add">Without a Byte Order Mark:</p> +<table diff="add" border="1" frame="border"><tbody><tr><td><code>00 00 00 3C</code></td> +<td rowspan="4">UCS-4 or other encoding with a 32-bit code unit and ASCII +characters encoded as ASCII values, in respectively big-endian (1234), little-endian +(4321) and two unusual byte orders (2143 and 3412). The encoding declaration +must be read to determine which of UCS-4 or other supported 32-bit encodings +applies.</td></tr><tr><td><code>3C 00 00 00</code></td> +<!--<td>UCS-4, little-endian machine (4321 order)</td>--> +</tr><tr><td><code>00 00 3C 00</code></td> +<!--<td>UCS-4, unusual octet order (2143)</td>--> +</tr><tr><td><code>00 3C 00 00</code></td> +<!--<td>UCS-4, unusual octet order (3412)</td>--> +</tr><tr><td><code>00 3C 00 3F</code></td><td>UTF-16BE or big-endian ISO-10646-UCS-2 +or other encoding with a 16-bit code unit in big-endian order and ASCII characters +encoded as ASCII values (the encoding declaration must be read to determine +which)</td></tr><tr><td><code>3C 00 3F 00</code></td><td>UTF-16LE or little-endian +ISO-10646-UCS-2 or other encoding with a 16-bit code unit in little-endian +order and ASCII characters encoded as ASCII values (the encoding declaration +must be read to determine which)</td></tr><tr><td><code>3C 3F 78 6D</code></td> +<td>UTF-8, ISO 646, ASCII, some part of ISO 8859, Shift-JIS, EUC, or any other +7-bit, 8-bit, or mixed-width encoding which ensures that the characters of +ASCII have their normal positions, width, and values; the actual encoding +declaration must be read to detect which of these applies, but since all of +these encodings use the same bit patterns for the relevant ASCII characters, +the encoding declaration itself may be read reliably</td></tr><tr><td><code>4C +6F A7 94</code></td><td>EBCDIC (in some flavor; the full encoding declaration +must be read to tell which code page is in use)</td></tr><tr><td>Other</td> +<td>UTF-8 without an encoding declaration, or else the data stream is mislabeled +(lacking a required encoding declaration), corrupt, fragmentary, or enclosed +in a wrapper of some kind</td></tr></tbody></table> +<note diff="add"> +<p>In cases above which do not require reading the encoding declaration to +determine the encoding, section 4.3.3 still requires that the encoding declaration, +if present, be read and that the encoding name be checked to match the actual +encoding of the entity. Also, it is possible that new character encodings +will be invented that will make it necessary to use the encoding declaration +to determine the encoding, in cases where this is not required at present.</p> +</note> +<p>This level of autodetection is enough to read the XML encoding declaration +and parse the character-encoding identifier, which is still necessary to distinguish +the individual members of each family of encodings (e.g. to tell UTF-8 from +8859, and the parts of 8859 from each other, or to distinguish the specific +EBCDIC code page in use, and so on).</p> +<p>Because the contents of the encoding declaration are restricted to <phrase +diff="chg">characters from the ASCII repertoire (however encoded)</phrase>, +a processor can reliably read the entire encoding declaration as soon as it +has detected which family of encodings is in use. Since in practice, all widely +used character encodings fall into one of the categories above, the XML encoding +declaration allows reasonably reliable in-band labeling of character encodings, +even when external sources of information at the operating-system or transport-protocol +level are unreliable. <phrase diff="del">Note that since external parsed entities +in UTF-16 may begin with any character, this autodetection does not always +work. Also, </phrase><phrase diff="add">Character encodings such as UTF-7 +that make overloaded usage of ASCII-valued bytes may fail to be reliably detected.</phrase></p> +<p>Once the processor has detected the character encoding in use, it can act +appropriately, whether by invoking a separate input routine for each case, +or by calling the proper conversion function on each character of input.</p> +<p>Like any self-labeling system, the XML encoding declaration will not work +if any software changes the entity's character set or encoding without updating +the encoding declaration. Implementors of character-encoding routines should +be careful to ensure the accuracy of the internal and external information +used to label the entity.</p> +</div2> +<div2 id="sec-guessing-with-ext-info"> +<head diff="add">Priorities in the Presence of External Encoding Information</head> +<p>The second possible case occurs when the XML entity is accompanied by encoding +information, as in some file systems and some network protocols. When multiple +sources of information are available, their relative priority and the preferred +method of handling conflict should be specified as part of the higher-level +protocol used to deliver XML. <phrase diff="chg">In particular, please refer +to <bibref ref="rfc2376"/> or its successor, which defines the <code>text/xml</code> +and <code>application/xml</code> MIME types and provides some useful guidance. +In the interests of interoperability, however, the following rule is recommended.</phrase></p> +<ulist> +<item><p>If an XML entity is in a file, the Byte-Order Mark and encoding declaration <phrase +diff="del">PI </phrase>are used (if present) to determine the character encoding.<phrase +diff="del"><loc role="erratumref" href="http://www.w3.org/XML/xml-19980210-errata#E74">[E74]</loc> +All other heuristics and sources of information are solely for error recovery.</phrase></p> +</item> +</ulist> +<ulist diff="del"> +<item><p>If an XML entity is delivered with a MIME type of text/xml, then +the <code>charset</code> parameter on the MIME type determines the character +encoding method; all other heuristics and sources of information are solely +for error recovery.</p></item> +<item><p>If an XML entity is delivered with a MIME type of application/xml, +then the Byte-Order Mark and encoding-declaration PI are used (if present) +to determine the character encoding. All other heuristics and sources of information +are solely for error recovery.</p></item> +</ulist> +<p diff="del">These rules apply only in the absence of protocol-level documentation; +in particular, when the MIME types text/xml and application/xml are defined, +the recommendations of the relevant RFC will supersede these rules.</p> +</div2> +</inform-div1> +<inform-div1 id="sec-xml-wg"> +<head>W3C XML Working Group</head> +<p>This specification was prepared and approved for publication by the W3C +XML Working Group (WG). WG approval of this specification does not necessarily +imply that all WG members voted for its approval. The current and former members +of the XML WG are:</p> +<orglist> +<member><name>Jon Bosak</name><affiliation>Sun</affiliation><role>Chair</role> +</member> +<member><name>James Clark</name><role>Technical Lead</role></member> +<member><name>Tim Bray</name><affiliation>Textuality and Netscape</affiliation> +<role>XML Co-editor</role></member> +<member><name>Jean Paoli</name><affiliation>Microsoft</affiliation><role>XML +Co-editor</role></member> +<member><name>C. M. Sperberg-McQueen</name><affiliation>U. of Ill.</affiliation> +<role>XML Co-editor</role></member> +<member><name>Dan Connolly</name><affiliation>W3C</affiliation><role>W3C Liaison</role> +</member> +<member><name>Paula Angerstein</name><affiliation>Texcel</affiliation></member> +<member><name>Steve DeRose</name><affiliation>INSO</affiliation></member> +<member><name>Dave Hollander</name><affiliation>HP</affiliation></member> +<member><name>Eliot Kimber</name><affiliation>ISOGEN</affiliation></member> +<member><name>Eve Maler</name><affiliation>ArborText</affiliation></member> +<member><name>Tom Magliery</name><affiliation>NCSA</affiliation></member> +<member><name>Murray Maloney</name><affiliation diff="chg">SoftQuad, Grif +SA, Muzmo and Veo Systems</affiliation></member> +<member><name diff="chg">MURATA Makoto (FAMILY Given)</name><affiliation>Fuji +Xerox Information Systems</affiliation></member> +<member><name>Joel Nava</name><affiliation>Adobe</affiliation></member> +<member><name>Conleth O'Connell</name><affiliation>Vignette</affiliation> +</member> +<member><name>Peter Sharpe</name><affiliation>SoftQuad</affiliation></member> +<member><name>John Tigue</name><affiliation>DataChannel</affiliation></member> +</orglist> +</inform-div1> +<inform-div1 id="sec-core-wg" diff="add"> +<head>W3C XML Core Group</head> +<p>The second edition of this specification was prepared by the W3C XML Core +Working Group (WG). The members of the WG at the time of publication of this +edition were:</p> +<orglist> +<member><name>Paula Angerstein</name><affiliation>Vignette</affiliation></member> +<member><name>Daniel Austin</name><affiliation>Ask Jeeves</affiliation></member> +<member><name>Tim Boland</name></member> +<member><name>Allen Brown</name><affiliation>Microsoft</affiliation></member> +<member><name>Dan Connolly</name><affiliation>W3C</affiliation><role>Staff +Contact</role></member> +<member><name>John Cowan</name><affiliation>Reuters Limited</affiliation> +</member> +<member><name>John Evdemon</name><affiliation>XMLSolutions Corporation</affiliation> +</member> +<member><name>Paul Grosso</name><affiliation>Arbortext</affiliation><role>Co-Chair</role> +</member> +<member><name>Arnaud Le Hors</name><affiliation>IBM</affiliation><role>Co-Chair</role> +</member> +<member><name>Eve Maler</name><affiliation>Sun Microsystems</affiliation> +<role>Second Edition Editor</role></member> +<member><name>Jonathan Marsh</name><affiliation>Microsoft</affiliation></member> +<member><name>MURATA Makoto (FAMILY Given)</name><affiliation>IBM</affiliation> +</member> +<member><name>Mark Needleman</name><affiliation>Data Research Associates</affiliation> +</member> +<member><name>David Orchard</name><affiliation>Jamcracker</affiliation></member> +<member><name>Lew Shannon</name><affiliation>NCR</affiliation></member> +<member><name>Richard Tobin</name><affiliation>University of Edinburgh</affiliation> +</member> +<member><name>Daniel Veillard</name><affiliation>W3C</affiliation></member> +<member><name>Dan Vint</name><affiliation>Lexica</affiliation></member> +<member><name>Norman Walsh</name><affiliation>Sun Microsystems</affiliation> +</member> +<member><name>François Yergeau</name><affiliation>Alis Technologies</affiliation> +<role>Errata List Editor</role></member> +<member><name>Kongyi Zhou</name><affiliation>Oracle</affiliation></member> +</orglist> +</inform-div1> +<inform-div1 diff="add"> +<head>Production Notes</head> +<p>This Second Edition was encoded in the <loc href="http://www.w3.org/XML/1998/06/xmlspec-v21.dtd">XMLspec +DTD</loc> (which has <loc href="http://www.w3.org/XML/1998/06/xmlspec-report-v21.htm">documentation</loc> +available). The HTML versions were produced with a combination of the <loc +href="http://www.w3.org/XML/1998/06/xmlspec.xsl">xmlspec.xsl</loc>, <loc href="http://www.w3.org/XML/1998/06/diffspec.xsl">diffspec.xsl</loc>, +and <loc href="http://www.w3.org/XML/1998/06/REC-xml-2e.xsl">REC-xml-2e.xsl</loc> +XSLT stylesheets. The PDF version was produced with the <loc href="http://www.tdb.uu.se/~jan/html2ps.html">html2ps</loc> +facility and a distiller program.</p> +</inform-div1> +</back></spec> |