Adding upstream version 1.21.22.upstream/1.21.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 4324 insertions, 0 deletions

diff --git a/doc/Doxyfile.in b/doc/Doxyfile.in
new file mode 100644
index 0000000..3faf8a4
--- /dev/null
+++ b/doc/Doxyfile.in
@@ -0,0 +1,2681 @@
+# Doxyfile 1.9.4
+
+# This file describes the settings to be used by the documentation system
+# doxygen (www.doxygen.org) for a project.
+#
+# All text after a double hash (##) is considered a comment and is placed in
+# front of the TAG it is preceding.
+#
+# All text after a single hash (#) is considered a comment and will be ignored.
+# The format is:
+# TAG = value [value, ...]
+# For lists, items can also be appended using:
+# TAG += value [value, ...]
+# Values that contain spaces should be placed between quotes (\" \").
+#
+# Note:
+#
+# Use doxygen to compare the used configuration file with the template
+# configuration file:
+# doxygen -x [configFile]
+# Use doxygen to compare the used configuration file with the template
+# configuration file without replacing the environment variables:
+# doxygen -x_noenv [configFile]
+
+#---------------------------------------------------------------------------
+# Project related configuration options
+#---------------------------------------------------------------------------
+
+# This tag specifies the encoding used for all characters in the configuration
+# file that follow. The default is UTF-8 which is also the encoding used for all
+# text before the first occurrence of this tag. Doxygen uses libiconv (or the
+# iconv built into libc) for the transcoding. See
+# https://www.gnu.org/software/libiconv/ for the list of possible encodings.
+# The default value is: UTF-8.
+
+DOXYFILE_ENCODING      = UTF-8
+
+# The PROJECT_NAME tag is a single word (or a sequence of words surrounded by
+# double-quotes, unless you are using Doxywizard) that should identify the
+# project for which the documentation is generated. This name is used in the
+# title of most generated pages and in a few other places.
+# The default value is: My Project.
+
+PROJECT_NAME           = @PACKAGE@
+
+# The PROJECT_NUMBER tag can be used to enter a project or revision number. This
+# could be handy for archiving the generated documentation or if some version
+# control system is used.
+
+PROJECT_NUMBER         = @VERSION@
+
+# Using the PROJECT_BRIEF tag one can provide an optional one line description
+# for a project that appears at the top of each page and should give viewer a
+# quick idea about the purpose of the project. Keep the description short.
+
+PROJECT_BRIEF          =
+
+# With the PROJECT_LOGO tag one can specify a logo or an icon that is included
+# in the documentation. The maximum height of the logo should not exceed 55
+# pixels and the maximum width should not exceed 200 pixels. Doxygen will copy
+# the logo to the output directory.
+
+PROJECT_LOGO           =
+
+# The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) path
+# into which the generated documentation will be written. If a relative path is
+# entered, it will be relative to the location where doxygen was started. If
+# left blank the current directory will be used.
+
+OUTPUT_DIRECTORY       = doc/
+
+# If the CREATE_SUBDIRS tag is set to YES then doxygen will create up to 4096
+# sub-directories (in 2 levels) under the output directory of each output format
+# and will distribute the generated files over these directories. Enabling this
+# option can be useful when feeding doxygen a huge amount of source files, where
+# putting all generated files in the same directory would otherwise causes
+# performance problems for the file system. Adapt CREATE_SUBDIRS_LEVEL to
+# control the number of sub-directories.
+# The default value is: NO.
+
+CREATE_SUBDIRS         = NO
+
+# Controls the number of sub-directories that will be created when
+# CREATE_SUBDIRS tag is set to YES. Level 0 represents 16 directories, and every
+# level increment doubles the number of directories, resulting in 4096
+# directories at level 8 which is the default and also the maximum value. The
+# sub-directories are organized in 2 levels, the first level always has a fixed
+# number of 16 directories.
+# Minimum value: 0, maximum value: 8, default value: 8.
+# This tag requires that the tag CREATE_SUBDIRS is set to YES.
+
+CREATE_SUBDIRS_LEVEL   = 8
+
+# If the ALLOW_UNICODE_NAMES tag is set to YES, doxygen will allow non-ASCII
+# characters to appear in the names of generated files. If set to NO, non-ASCII
+# characters will be escaped, for example _xE3_x81_x84 will be used for Unicode
+# U+3044.
+# The default value is: NO.
+
+ALLOW_UNICODE_NAMES    = NO
+
+# The OUTPUT_LANGUAGE tag is used to specify the language in which all
+# documentation generated by doxygen is written. Doxygen will use this
+# information to generate all constant output in the proper language.
+# Possible values are: Afrikaans, Arabic, Armenian, Brazilian, Bulgarian,
+# Catalan, Chinese, Chinese-Traditional, Croatian, Czech, Danish, Dutch, English
+# (United States), Esperanto, Farsi (Persian), Finnish, French, German, Greek,
+# Hindi, Hungarian, Indonesian, Italian, Japanese, Japanese-en (Japanese with
+# English messages), Korean, Korean-en (Korean with English messages), Latvian,
+# Lithuanian, Macedonian, Norwegian, Persian (Farsi), Polish, Portuguese,
+# Romanian, Russian, Serbian, Serbian-Cyrillic, Slovak, Slovene, Spanish,
+# Swedish, Turkish, Ukrainian and Vietnamese.
+# The default value is: English.
+
+OUTPUT_LANGUAGE        = English
+
+# If the BRIEF_MEMBER_DESC tag is set to YES, doxygen will include brief member
+# descriptions after the members that are listed in the file and class
+# documentation (similar to Javadoc). Set to NO to disable this.
+# The default value is: YES.
+
+BRIEF_MEMBER_DESC      = YES
+
+# If the REPEAT_BRIEF tag is set to YES, doxygen will prepend the brief
+# description of a member or function before the detailed description
+#
+# Note: If both HIDE_UNDOC_MEMBERS and BRIEF_MEMBER_DESC are set to NO, the
+# brief descriptions will be completely suppressed.
+# The default value is: YES.
+
+REPEAT_BRIEF           = YES
+
+# This tag implements a quasi-intelligent brief description abbreviator that is
+# used to form the text in various listings. Each string in this list, if found
+# as the leading text of the brief description, will be stripped from the text
+# and the result, after processing the whole list, is used as the annotated
+# text. Otherwise, the brief description is used as-is. If left blank, the
+# following values are used ($name is automatically replaced with the name of
+# the entity):The $name class, The $name widget, The $name file, is, provides,
+# specifies, contains, represents, a, an and the.
+
+ABBREVIATE_BRIEF       =
+
+# If the ALWAYS_DETAILED_SEC and REPEAT_BRIEF tags are both set to YES then
+# doxygen will generate a detailed section even if there is only a brief
+# description.
+# The default value is: NO.
+
+ALWAYS_DETAILED_SEC    = NO
+
+# If the INLINE_INHERITED_MEMB tag is set to YES, doxygen will show all
+# inherited members of a class in the documentation of that class as if those
+# members were ordinary class members. Constructors, destructors and assignment
+# operators of the base classes will not be shown.
+# The default value is: NO.
+
+INLINE_INHERITED_MEMB  = NO
+
+# If the FULL_PATH_NAMES tag is set to YES, doxygen will prepend the full path
+# before files name in the file list and in the header files. If set to NO the
+# shortest path that makes the file name unique will be used
+# The default value is: YES.
+
+FULL_PATH_NAMES        = YES
+
+# The STRIP_FROM_PATH tag can be used to strip a user-defined part of the path.
+# Stripping is only done if one of the specified strings matches the left-hand
+# part of the path. The tag can be used to show relative paths in the file list.
+# If left blank the directory from which doxygen is run is used as the path to
+# strip.
+#
+# Note that you can specify absolute paths here, but also relative paths, which
+# will be relative from the directory where doxygen is started.
+# This tag requires that the tag FULL_PATH_NAMES is set to YES.
+
+STRIP_FROM_PATH        =
+
+# The STRIP_FROM_INC_PATH tag can be used to strip a user-defined part of the
+# path mentioned in the documentation of a class, which tells the reader which
+# header file to include in order to use a class. If left blank only the name of
+# the header file containing the class definition is used. Otherwise one should
+# specify the list of include paths that are normally passed to the compiler
+# using the -I flag.
+
+STRIP_FROM_INC_PATH    =
+
+# If the SHORT_NAMES tag is set to YES, doxygen will generate much shorter (but
+# less readable) file names. This can be useful is your file systems doesn't
+# support long names like on DOS, Mac, or CD-ROM.
+# The default value is: NO.
+
+SHORT_NAMES            = NO
+
+# If the JAVADOC_AUTOBRIEF tag is set to YES then doxygen will interpret the
+# first line (until the first dot) of a Javadoc-style comment as the brief
+# description. If set to NO, the Javadoc-style will behave just like regular Qt-
+# style comments (thus requiring an explicit @brief command for a brief
+# description.)
+# The default value is: NO.
+
+JAVADOC_AUTOBRIEF      = YES
+
+# If the JAVADOC_BANNER tag is set to YES then doxygen will interpret a line
+# such as
+# /***************
+# as being the beginning of a Javadoc-style comment "banner". If set to NO, the
+# Javadoc-style will behave just like regular comments and it will not be
+# interpreted by doxygen.
+# The default value is: NO.
+
+JAVADOC_BANNER         = NO
+
+# If the QT_AUTOBRIEF tag is set to YES then doxygen will interpret the first
+# line (until the first dot) of a Qt-style comment as the brief description. If
+# set to NO, the Qt-style will behave just like regular Qt-style comments (thus
+# requiring an explicit \brief command for a brief description.)
+# The default value is: NO.
+
+QT_AUTOBRIEF           = NO
+
+# The MULTILINE_CPP_IS_BRIEF tag can be set to YES to make doxygen treat a
+# multi-line C++ special comment block (i.e. a block of //! or /// comments) as
+# a brief description. This used to be the default behavior. The new default is
+# to treat a multi-line C++ comment block as a detailed description. Set this
+# tag to YES if you prefer the old behavior instead.
+#
+# Note that setting this tag to YES also means that rational rose comments are
+# not recognized any more.
+# The default value is: NO.
+
+MULTILINE_CPP_IS_BRIEF = NO
+
+# By default Python docstrings are displayed as preformatted text and doxygen's
+# special commands cannot be used. By setting PYTHON_DOCSTRING to NO the
+# doxygen's special commands can be used and the contents of the docstring
+# documentation blocks is shown as doxygen documentation.
+# The default value is: YES.
+
+PYTHON_DOCSTRING       = YES
+
+# If the INHERIT_DOCS tag is set to YES then an undocumented member inherits the
+# documentation from any documented member that it re-implements.
+# The default value is: YES.
+
+INHERIT_DOCS           = YES
+
+# If the SEPARATE_MEMBER_PAGES tag is set to YES then doxygen will produce a new
+# page for each member. If set to NO, the documentation of a member will be part
+# of the file/class/namespace that contains it.
+# The default value is: NO.
+
+SEPARATE_MEMBER_PAGES  = NO
+
+# The TAB_SIZE tag can be used to set the number of spaces in a tab. Doxygen
+# uses this value to replace tabs by spaces in code fragments.
+# Minimum value: 1, maximum value: 16, default value: 4.
+
+TAB_SIZE               = 8
+
+# This tag can be used to specify a number of aliases that act as commands in
+# the documentation. An alias has the form:
+# name=value
+# For example adding
+# "sideeffect=@par Side Effects:^^"
+# will allow you to put the command \sideeffect (or @sideeffect) in the
+# documentation, which will result in a user-defined paragraph with heading
+# "Side Effects:". Note that you cannot put \n's in the value part of an alias
+# to insert newlines (in the resulting output). You can put ^^ in the value part
+# of an alias to insert a newline as if a physical newline was in the original
+# file. When you need a literal { or } or , in the value part of an alias you
+# have to escape them by means of a backslash (\), this can lead to conflicts
+# with the commands \{ and \} for these it is advised to use the version @{ and
+# @} or use a double escape (\\{ and \\})
+
+ALIASES                =
+
+# Set the OPTIMIZE_OUTPUT_FOR_C tag to YES if your project consists of C sources
+# only. Doxygen will then generate output that is more tailored for C. For
+# instance, some of the names that are used will be different. The list of all
+# members will be omitted, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_FOR_C  = YES
+
+# Set the OPTIMIZE_OUTPUT_JAVA tag to YES if your project consists of Java or
+# Python sources only. Doxygen will then generate output that is more tailored
+# for that language. For instance, namespaces will be presented as packages,
+# qualified scopes will look different, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_JAVA   = NO
+
+# Set the OPTIMIZE_FOR_FORTRAN tag to YES if your project consists of Fortran
+# sources. Doxygen will then generate output that is tailored for Fortran.
+# The default value is: NO.
+
+OPTIMIZE_FOR_FORTRAN   = NO
+
+# Set the OPTIMIZE_OUTPUT_VHDL tag to YES if your project consists of VHDL
+# sources. Doxygen will then generate output that is tailored for VHDL.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_VHDL   = NO
+
+# Set the OPTIMIZE_OUTPUT_SLICE tag to YES if your project consists of Slice
+# sources only. Doxygen will then generate output that is more tailored for that
+# language. For instance, namespaces will be presented as modules, types will be
+# separated into more groups, etc.
+# The default value is: NO.
+
+OPTIMIZE_OUTPUT_SLICE  = NO
+
+# Doxygen selects the parser to use depending on the extension of the files it
+# parses. With this tag you can assign which parser to use for a given
+# extension. Doxygen has a built-in mapping, but you can override or extend it
+# using this tag. The format is ext=language, where ext is a file extension, and
+# language is one of the parsers supported by doxygen: IDL, Java, JavaScript,
+# Csharp (C#), C, C++, Lex, D, PHP, md (Markdown), Objective-C, Python, Slice,
+# VHDL, Fortran (fixed format Fortran: FortranFixed, free formatted Fortran:
+# FortranFree, unknown formatted Fortran: Fortran. In the later case the parser
+# tries to guess whether the code is fixed or free formatted code, this is the
+# default for Fortran type files). For instance to make doxygen treat .inc files
+# as Fortran files (default is PHP), and .f files as C (default is Fortran),
+# use: inc=Fortran f=C.
+#
+# Note: For files without extension you can use no_extension as a placeholder.
+#
+# Note that for custom extensions you also need to set FILE_PATTERNS otherwise
+# the files are not read by doxygen. When specifying no_extension you should add
+# * to the FILE_PATTERNS.
+#
+# Note see also the list of default file extension mappings.
+
+EXTENSION_MAPPING      = l=C
+
+# If the MARKDOWN_SUPPORT tag is enabled then doxygen pre-processes all comments
+# according to the Markdown format, which allows for more readable
+# documentation. See https://daringfireball.net/projects/markdown/ for details.
+# The output of markdown processing is further processed by doxygen, so you can
+# mix doxygen, HTML, and XML commands with Markdown formatting. Disable only in
+# case of backward compatibilities issues.
+# The default value is: YES.
+
+MARKDOWN_SUPPORT       = YES
+
+# When the TOC_INCLUDE_HEADINGS tag is set to a non-zero value, all headings up
+# to that level are automatically included in the table of contents, even if
+# they do not have an id attribute.
+# Note: This feature currently applies only to Markdown headings.
+# Minimum value: 0, maximum value: 99, default value: 5.
+# This tag requires that the tag MARKDOWN_SUPPORT is set to YES.
+
+TOC_INCLUDE_HEADINGS   = 0
+
+# When enabled doxygen tries to link words that correspond to documented
+# classes, or namespaces to their corresponding documentation. Such a link can
+# be prevented in individual cases by putting a % sign in front of the word or
+# globally by setting AUTOLINK_SUPPORT to NO.
+# The default value is: YES.
+
+AUTOLINK_SUPPORT       = YES
+
+# If you use STL classes (i.e. std::string, std::vector, etc.) but do not want
+# to include (a tag file for) the STL sources as input, then you should set this
+# tag to YES in order to let doxygen match functions declarations and
+# definitions whose arguments contain STL classes (e.g. func(std::string);
+# versus func(std::string) {}). This also make the inheritance and collaboration
+# diagrams that involve STL classes more complete and accurate.
+# The default value is: NO.
+
+BUILTIN_STL_SUPPORT    = NO
+
+# If you use Microsoft's C++/CLI language, you should set this option to YES to
+# enable parsing support.
+# The default value is: NO.
+
+CPP_CLI_SUPPORT        = NO
+
+# Set the SIP_SUPPORT tag to YES if your project consists of sip (see:
+# https://www.riverbankcomputing.com/software/sip/intro) sources only. Doxygen
+# will parse them like normal C++ but will assume all classes use public instead
+# of private inheritance when no explicit protection keyword is present.
+# The default value is: NO.
+
+SIP_SUPPORT            = NO
+
+# For Microsoft's IDL there are propget and propput attributes to indicate
+# getter and setter methods for a property. Setting this option to YES will make
+# doxygen to replace the get and set methods by a property in the documentation.
+# This will only work if the methods are indeed getting or setting a simple
+# type. If this is not the case, or you want to show the methods anyway, you
+# should set this option to NO.
+# The default value is: YES.
+
+IDL_PROPERTY_SUPPORT   = YES
+
+# If member grouping is used in the documentation and the DISTRIBUTE_GROUP_DOC
+# tag is set to YES then doxygen will reuse the documentation of the first
+# member in the group (if any) for the other members of the group. By default
+# all members of a group must be documented explicitly.
+# The default value is: NO.
+
+DISTRIBUTE_GROUP_DOC   = NO
+
+# If one adds a struct or class to a group and this option is enabled, then also
+# any nested class or struct is added to the same group. By default this option
+# is disabled and one has to add nested compounds explicitly via \ingroup.
+# The default value is: NO.
+
+GROUP_NESTED_COMPOUNDS = NO
+
+# Set the SUBGROUPING tag to YES to allow class member groups of the same type
+# (for instance a group of public functions) to be put as a subgroup of that
+# type (e.g. under the Public Functions section). Set it to NO to prevent
+# subgrouping. Alternatively, this can be done per class using the
+# \nosubgrouping command.
+# The default value is: YES.
+
+SUBGROUPING            = YES
+
+# When the INLINE_GROUPED_CLASSES tag is set to YES, classes, structs and unions
+# are shown inside the group in which they are included (e.g. using \ingroup)
+# instead of on a separate page (for HTML and Man pages) or section (for LaTeX
+# and RTF).
+#
+# Note that this feature does not work in combination with
+# SEPARATE_MEMBER_PAGES.
+# The default value is: NO.
+
+INLINE_GROUPED_CLASSES = NO
+
+# When the INLINE_SIMPLE_STRUCTS tag is set to YES, structs, classes, and unions
+# with only public data fields or simple typedef fields will be shown inline in
+# the documentation of the scope in which they are defined (i.e. file,
+# namespace, or group documentation), provided this scope is documented. If set
+# to NO, structs, classes, and unions are shown on a separate page (for HTML and
+# Man pages) or section (for LaTeX and RTF).
+# The default value is: NO.
+
+INLINE_SIMPLE_STRUCTS  = NO
+
+# When TYPEDEF_HIDES_STRUCT tag is enabled, a typedef of a struct, union, or
+# enum is documented as struct, union, or enum with the name of the typedef. So
+# typedef struct TypeS {} TypeT, will appear in the documentation as a struct
+# with name TypeT. When disabled the typedef will appear as a member of a file,
+# namespace, or class. And the struct will be named TypeS. This can typically be
+# useful for C code in case the coding convention dictates that all compound
+# types are typedef'ed and only the typedef is referenced, never the tag name.
+# The default value is: NO.
+
+TYPEDEF_HIDES_STRUCT   = NO
+
+# The size of the symbol lookup cache can be set using LOOKUP_CACHE_SIZE. This
+# cache is used to resolve symbols given their name and scope. Since this can be
+# an expensive process and often the same symbol appears multiple times in the
+# code, doxygen keeps a cache of pre-resolved symbols. If the cache is too small
+# doxygen will become slower. If the cache is too large, memory is wasted. The
+# cache size is given by this formula: 2^(16+LOOKUP_CACHE_SIZE). The valid range
+# is 0..9, the default is 0, corresponding to a cache size of 2^16=65536
+# symbols. At the end of a run doxygen will report the cache usage and suggest
+# the optimal cache size from a speed point of view.
+# Minimum value: 0, maximum value: 9, default value: 0.
+
+LOOKUP_CACHE_SIZE      = 0
+
+# The NUM_PROC_THREADS specifies the number of threads doxygen is allowed to use
+# during processing. When set to 0 doxygen will based this on the number of
+# cores available in the system. You can set it explicitly to a value larger
+# than 0 to get more control over the balance between CPU load and processing
+# speed. At this moment only the input processing can be done using multiple
+# threads. Since this is still an experimental feature the default is set to 1,
+# which effectively disables parallel processing. Please report any issues you
+# encounter. Generating dot graphs in parallel is controlled by the
+# DOT_NUM_THREADS setting.
+# Minimum value: 0, maximum value: 32, default value: 1.
+
+NUM_PROC_THREADS       = 1
+
+#---------------------------------------------------------------------------
+# Build related configuration options
+#---------------------------------------------------------------------------
+
+# If the EXTRACT_ALL tag is set to YES, doxygen will assume all entities in
+# documentation are documented, even if no documentation was available. Private
+# class members and static file members will be hidden unless the
+# EXTRACT_PRIVATE respectively EXTRACT_STATIC tags are set to YES.
+# Note: This will also disable the warnings about undocumented members that are
+# normally produced when WARNINGS is set to YES.
+# The default value is: NO.
+
+EXTRACT_ALL            = @BUILD_DEVEL_DOCS@
+
+# If the EXTRACT_PRIVATE tag is set to YES, all private members of a class will
+# be included in the documentation.
+# The default value is: NO.
+
+EXTRACT_PRIVATE        = NO
+
+# If the EXTRACT_PRIV_VIRTUAL tag is set to YES, documented private virtual
+# methods of a class will be included in the documentation.
+# The default value is: NO.
+
+EXTRACT_PRIV_VIRTUAL   = NO
+
+# If the EXTRACT_PACKAGE tag is set to YES, all members with package or internal
+# scope will be included in the documentation.
+# The default value is: NO.
+
+EXTRACT_PACKAGE        = NO
+
+# If the EXTRACT_STATIC tag is set to YES, all static members of a file will be
+# included in the documentation.
+# The default value is: NO.
+
+EXTRACT_STATIC         = NO
+
+# If the EXTRACT_LOCAL_CLASSES tag is set to YES, classes (and structs) defined
+# locally in source files will be included in the documentation. If set to NO,
+# only classes defined in header files are included. Does not have any effect
+# for Java sources.
+# The default value is: YES.
+
+EXTRACT_LOCAL_CLASSES  = YES
+
+# This flag is only useful for Objective-C code. If set to YES, local methods,
+# which are defined in the implementation section but not in the interface are
+# included in the documentation. If set to NO, only methods in the interface are
+# included.
+# The default value is: NO.
+
+EXTRACT_LOCAL_METHODS  = NO
+
+# If this flag is set to YES, the members of anonymous namespaces will be
+# extracted and appear in the documentation as a namespace called
+# 'anonymous_namespace{file}', where file will be replaced with the base name of
+# the file that contains the anonymous namespace. By default anonymous namespace
+# are hidden.
+# The default value is: NO.
+
+EXTRACT_ANON_NSPACES   = NO
+
+# If this flag is set to YES, the name of an unnamed parameter in a declaration
+# will be determined by the corresponding definition. By default unnamed
+# parameters remain unnamed in the output.
+# The default value is: YES.
+
+RESOLVE_UNNAMED_PARAMS = YES
+
+# If the HIDE_UNDOC_MEMBERS tag is set to YES, doxygen will hide all
+# undocumented members inside documented classes or files. If set to NO these
+# members will be included in the various overviews, but no documentation
+# section is generated. This option has no effect if EXTRACT_ALL is enabled.
+# The default value is: NO.
+
+HIDE_UNDOC_MEMBERS     = NO
+
+# If the HIDE_UNDOC_CLASSES tag is set to YES, doxygen will hide all
+# undocumented classes that are normally visible in the class hierarchy. If set
+# to NO, these classes will be included in the various overviews. This option
+# has no effect if EXTRACT_ALL is enabled.
+# The default value is: NO.
+
+HIDE_UNDOC_CLASSES     = NO
+
+# If the HIDE_FRIEND_COMPOUNDS tag is set to YES, doxygen will hide all friend
+# declarations. If set to NO, these declarations will be included in the
+# documentation.
+# The default value is: NO.
+
+HIDE_FRIEND_COMPOUNDS  = NO
+
+# If the HIDE_IN_BODY_DOCS tag is set to YES, doxygen will hide any
+# documentation blocks found inside the body of a function. If set to NO, these
+# blocks will be appended to the function's detailed documentation block.
+# The default value is: NO.
+
+HIDE_IN_BODY_DOCS      = NO
+
+# The INTERNAL_DOCS tag determines if documentation that is typed after a
+# \internal command is included. If the tag is set to NO then the documentation
+# will be excluded. Set it to YES to include the internal documentation.
+# The default value is: NO.
+
+INTERNAL_DOCS          = NO
+
+# With the correct setting of option CASE_SENSE_NAMES doxygen will better be
+# able to match the capabilities of the underlying filesystem. In case the
+# filesystem is case sensitive (i.e. it supports files in the same directory
+# whose names only differ in casing), the option must be set to YES to properly
+# deal with such files in case they appear in the input. For filesystems that
+# are not case sensitive the option should be set to NO to properly deal with
+# output files written for symbols that only differ in casing, such as for two
+# classes, one named CLASS and the other named Class, and to also support
+# references to files without having to specify the exact matching casing. On
+# Windows (including Cygwin) and MacOS, users should typically set this option
+# to NO, whereas on Linux or other Unix flavors it should typically be set to
+# YES.
+# The default value is: system dependent.
+
+CASE_SENSE_NAMES       = YES
+
+# If the HIDE_SCOPE_NAMES tag is set to NO then doxygen will show members with
+# their full class and namespace scopes in the documentation. If set to YES, the
+# scope will be hidden.
+# The default value is: NO.
+
+HIDE_SCOPE_NAMES       = NO
+
+# If the HIDE_COMPOUND_REFERENCE tag is set to NO (default) then doxygen will
+# append additional text to a page's title, such as Class Reference. If set to
+# YES the compound reference will be hidden.
+# The default value is: NO.
+
+HIDE_COMPOUND_REFERENCE= NO
+
+# If the SHOW_HEADERFILE tag is set to YES then the documentation for a class
+# will show which file needs to be included to use the class.
+# The default value is: YES.
+
+SHOW_HEADERFILE        = YES
+
+# If the SHOW_INCLUDE_FILES tag is set to YES then doxygen will put a list of
+# the files that are included by a file in the documentation of that file.
+# The default value is: YES.
+
+SHOW_INCLUDE_FILES     = YES
+
+# If the SHOW_GROUPED_MEMB_INC tag is set to YES then Doxygen will add for each
+# grouped member an include statement to the documentation, telling the reader
+# which file to include in order to use the member.
+# The default value is: NO.
+
+SHOW_GROUPED_MEMB_INC  = NO
+
+# If the FORCE_LOCAL_INCLUDES tag is set to YES then doxygen will list include
+# files with double quotes in the documentation rather than with sharp brackets.
+# The default value is: NO.
+
+FORCE_LOCAL_INCLUDES   = NO
+
+# If the INLINE_INFO tag is set to YES then a tag [inline] is inserted in the
+# documentation for inline members.
+# The default value is: YES.
+
+INLINE_INFO            = YES
+
+# If the SORT_MEMBER_DOCS tag is set to YES then doxygen will sort the
+# (detailed) documentation of file and class members alphabetically by member
+# name. If set to NO, the members will appear in declaration order.
+# The default value is: YES.
+
+SORT_MEMBER_DOCS       = YES
+
+# If the SORT_BRIEF_DOCS tag is set to YES then doxygen will sort the brief
+# descriptions of file, namespace and class members alphabetically by member
+# name. If set to NO, the members will appear in declaration order. Note that
+# this will also influence the order of the classes in the class list.
+# The default value is: NO.
+
+SORT_BRIEF_DOCS        = NO
+
+# If the SORT_MEMBERS_CTORS_1ST tag is set to YES then doxygen will sort the
+# (brief and detailed) documentation of class members so that constructors and
+# destructors are listed first. If set to NO the constructors will appear in the
+# respective orders defined by SORT_BRIEF_DOCS and SORT_MEMBER_DOCS.
+# Note: If SORT_BRIEF_DOCS is set to NO this option is ignored for sorting brief
+# member documentation.
+# Note: If SORT_MEMBER_DOCS is set to NO this option is ignored for sorting
+# detailed member documentation.
+# The default value is: NO.
+
+SORT_MEMBERS_CTORS_1ST = NO
+
+# If the SORT_GROUP_NAMES tag is set to YES then doxygen will sort the hierarchy
+# of group names into alphabetical order. If set to NO the group names will
+# appear in their defined order.
+# The default value is: NO.
+
+SORT_GROUP_NAMES       = NO
+
+# If the SORT_BY_SCOPE_NAME tag is set to YES, the class list will be sorted by
+# fully-qualified names, including namespaces. If set to NO, the class list will
+# be sorted only by class name, not including the namespace part.
+# Note: This option is not very useful if HIDE_SCOPE_NAMES is set to YES.
+# Note: This option applies only to the class list, not to the alphabetical
+# list.
+# The default value is: NO.
+
+SORT_BY_SCOPE_NAME     = NO
+
+# If the STRICT_PROTO_MATCHING option is enabled and doxygen fails to do proper
+# type resolution of all parameters of a function it will reject a match between
+# the prototype and the implementation of a member function even if there is
+# only one candidate or it is obvious which candidate to choose by doing a
+# simple string match. By disabling STRICT_PROTO_MATCHING doxygen will still
+# accept a match between prototype and implementation in such cases.
+# The default value is: NO.
+
+STRICT_PROTO_MATCHING  = NO
+
+# The GENERATE_TODOLIST tag can be used to enable (YES) or disable (NO) the todo
+# list. This list is created by putting \todo commands in the documentation.
+# The default value is: YES.
+
+GENERATE_TODOLIST      = YES
+
+# The GENERATE_TESTLIST tag can be used to enable (YES) or disable (NO) the test
+# list. This list is created by putting \test commands in the documentation.
+# The default value is: YES.
+
+GENERATE_TESTLIST      = YES
+
+# The GENERATE_BUGLIST tag can be used to enable (YES) or disable (NO) the bug
+# list. This list is created by putting \bug commands in the documentation.
+# The default value is: YES.
+
+GENERATE_BUGLIST       = YES
+
+# The GENERATE_DEPRECATEDLIST tag can be used to enable (YES) or disable (NO)
+# the deprecated list. This list is created by putting \deprecated commands in
+# the documentation.
+# The default value is: YES.
+
+GENERATE_DEPRECATEDLIST= YES
+
+# The ENABLED_SECTIONS tag can be used to enable conditional documentation
+# sections, marked by \if <section_label> ... \endif and \cond <section_label>
+# ... \endcond blocks.
+
+ENABLED_SECTIONS       =
+
+# The MAX_INITIALIZER_LINES tag determines the maximum number of lines that the
+# initial value of a variable or macro / define can have for it to appear in the
+# documentation. If the initializer consists of more lines than specified here
+# it will be hidden. Use a value of 0 to hide initializers completely. The
+# appearance of the value of individual variables and macros / defines can be
+# controlled using \showinitializer or \hideinitializer command in the
+# documentation regardless of this setting.
+# Minimum value: 0, maximum value: 10000, default value: 30.
+
+MAX_INITIALIZER_LINES  = 30
+
+# Set the SHOW_USED_FILES tag to NO to disable the list of files generated at
+# the bottom of the documentation of classes and structs. If set to YES, the
+# list will mention the files that were used to generate the documentation.
+# The default value is: YES.
+
+SHOW_USED_FILES        = YES
+
+# Set the SHOW_FILES tag to NO to disable the generation of the Files page. This
+# will remove the Files entry from the Quick Index and from the Folder Tree View
+# (if specified).
+# The default value is: YES.
+
+SHOW_FILES             = YES
+
+# Set the SHOW_NAMESPACES tag to NO to disable the generation of the Namespaces
+# page. This will remove the Namespaces entry from the Quick Index and from the
+# Folder Tree View (if specified).
+# The default value is: YES.
+
+SHOW_NAMESPACES        = YES
+
+# The FILE_VERSION_FILTER tag can be used to specify a program or script that
+# doxygen should invoke to get the current version for each file (typically from
+# the version control system). Doxygen will invoke the program by executing (via
+# popen()) the command command input-file, where command is the value of the
+# FILE_VERSION_FILTER tag, and input-file is the name of an input file provided
+# by doxygen. Whatever the program writes to standard output is used as the file
+# version. For an example see the documentation.
+
+FILE_VERSION_FILTER    = "git log -n 1 --pretty=format:%h --"
+
+# The LAYOUT_FILE tag can be used to specify a layout file which will be parsed
+# by doxygen. The layout file controls the global structure of the generated
+# output files in an output format independent way. To create the layout file
+# that represents doxygen's defaults, run doxygen with the -l option. You can
+# optionally specify a file name after the option, if omitted DoxygenLayout.xml
+# will be used as the name of the layout file. See also section "Changing the
+# layout of pages" for information.
+#
+# Note that if you run doxygen from a directory containing a file called
+# DoxygenLayout.xml, doxygen will parse it automatically even if the LAYOUT_FILE
+# tag is left empty.
+
+LAYOUT_FILE            =
+
+# The CITE_BIB_FILES tag can be used to specify one or more bib files containing
+# the reference definitions. This must be a list of .bib files. The .bib
+# extension is automatically appended if omitted. This requires the bibtex tool
+# to be installed. See also https://en.wikipedia.org/wiki/BibTeX for more info.
+# For LaTeX the style of the bibliography can be controlled using
+# LATEX_BIB_STYLE. To use this feature you need bibtex and perl available in the
+# search path. See also \cite for info how to create references.
+
+CITE_BIB_FILES         =
+
+#---------------------------------------------------------------------------
+# Configuration options related to warning and progress messages
+#---------------------------------------------------------------------------
+
+# The QUIET tag can be used to turn on/off the messages that are generated to
+# standard output by doxygen. If QUIET is set to YES this implies that the
+# messages are off.
+# The default value is: NO.
+
+QUIET                  = YES
+
+# The WARNINGS tag can be used to turn on/off the warning messages that are
+# generated to standard error (stderr) by doxygen. If WARNINGS is set to YES
+# this implies that the warnings are on.
+#
+# Tip: Turn warnings on while writing the documentation.
+# The default value is: YES.
+
+WARNINGS               = YES
+
+# If the WARN_IF_UNDOCUMENTED tag is set to YES then doxygen will generate
+# warnings for undocumented members. If EXTRACT_ALL is set to YES then this flag
+# will automatically be disabled.
+# The default value is: YES.
+
+WARN_IF_UNDOCUMENTED   = YES
+
+# If the WARN_IF_DOC_ERROR tag is set to YES, doxygen will generate warnings for
+# potential errors in the documentation, such as documenting some parameters in
+# a documented function twice, or documenting parameters that don't exist or
+# using markup commands wrongly.
+# The default value is: YES.
+
+WARN_IF_DOC_ERROR      = YES
+
+# If WARN_IF_INCOMPLETE_DOC is set to YES, doxygen will warn about incomplete
+# function parameter documentation. If set to NO, doxygen will accept that some
+# parameters have no documentation without warning.
+# The default value is: YES.
+
+WARN_IF_INCOMPLETE_DOC = YES
+
+# This WARN_NO_PARAMDOC option can be enabled to get warnings for functions that
+# are documented, but have no documentation for their parameters or return
+# value. If set to NO, doxygen will only warn about wrong parameter
+# documentation, but not about the absence of documentation. If EXTRACT_ALL is
+# set to YES then this flag will automatically be disabled. See also
+# WARN_IF_INCOMPLETE_DOC
+# The default value is: NO.
+
+WARN_NO_PARAMDOC       = NO
+
+# If the WARN_AS_ERROR tag is set to YES then doxygen will immediately stop when
+# a warning is encountered. If the WARN_AS_ERROR tag is set to FAIL_ON_WARNINGS
+# then doxygen will continue running as if WARN_AS_ERROR tag is set to NO, but
+# at the end of the doxygen process doxygen will return with a non-zero status.
+# Possible values are: NO, YES and FAIL_ON_WARNINGS.
+# The default value is: NO.
+
+WARN_AS_ERROR          = NO
+
+# The WARN_FORMAT tag determines the format of the warning messages that doxygen
+# can produce. The string should contain the $file, $line, and $text tags, which
+# will be replaced by the file and line number from which the warning originated
+# and the warning text. Optionally the format may contain $version, which will
+# be replaced by the version of the file (if it could be obtained via
+# FILE_VERSION_FILTER)
+# See also: WARN_LINE_FORMAT
+# The default value is: $file:$line: $text.
+
+WARN_FORMAT            = "$file:$line: $text"
+
+# In the $text part of the WARN_FORMAT command it is possible that a reference
+# to a more specific place is given. To make it easier to jump to this place
+# (outside of doxygen) the user can define a custom "cut" / "paste" string.
+# Example:
+# WARN_LINE_FORMAT = "'vi $file +$line'"
+# See also: WARN_FORMAT
+# The default value is: at line $line of file $file.
+
+WARN_LINE_FORMAT       = "at line $line of file $file"
+
+# The WARN_LOGFILE tag can be used to specify a file to which warning and error
+# messages should be written. If left blank the output is written to standard
+# error (stderr). In case the file specified cannot be opened for writing the
+# warning and error messages are written to standard error. When as file - is
+# specified the warning and error messages are written to standard output
+# (stdout).
+
+WARN_LOGFILE           =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the input files
+#---------------------------------------------------------------------------
+
+# The INPUT tag is used to specify the files and/or directories that contain
+# documented source files. You may enter file names like myfile.cpp or
+# directories like /usr/src/myproject. Separate the files or directories with
+# spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
+# Note: If this tag is empty the current directory is searched.
+
+INPUT                  = lib/dpkg \
+                         src \
+                         utils
+
+# This tag can be used to specify the character encoding of the source files
+# that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
+# libiconv (or the iconv built into libc) for the transcoding. See the libiconv
+# documentation (see:
+# https://www.gnu.org/software/libiconv/) for the list of possible encodings.
+# The default value is: UTF-8.
+
+INPUT_ENCODING         = UTF-8
+
+# If the value of the INPUT tag contains directories, you can use the
+# FILE_PATTERNS tag to specify one or more wildcard patterns (like *.cpp and
+# *.h) to filter out the source-files in the directories.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# read by doxygen.
+#
+# Note the list of default checked file patterns might differ from the list of
+# default file extension mappings.
+#
+# If left blank the following patterns are tested:*.c, *.cc, *.cxx, *.cpp,
+# *.c++, *.java, *.ii, *.ixx, *.ipp, *.i++, *.inl, *.idl, *.ddl, *.odl, *.h,
+# *.hh, *.hxx, *.hpp, *.h++, *.l, *.cs, *.d, *.php, *.php4, *.php5, *.phtml,
+# *.inc, *.m, *.markdown, *.md, *.mm, *.dox (to be provided as doxygen C
+# comment), *.py, *.pyw, *.f90, *.f95, *.f03, *.f08, *.f18, *.f, *.for, *.vhd,
+# *.vhdl, *.ucf, *.qsf and *.ice.
+
+FILE_PATTERNS          = *.c \
+                         *.h
+
+# The RECURSIVE tag can be used to specify whether or not subdirectories should
+# be searched for input files as well.
+# The default value is: NO.
+
+RECURSIVE              = YES
+
+# The EXCLUDE tag can be used to specify files and/or directories that should be
+# excluded from the INPUT source files. This way you can easily exclude a
+# subdirectory from a directory tree whose root is specified with the INPUT tag.
+#
+# Note that relative paths are relative to the directory from which doxygen is
+# run.
+
+EXCLUDE                =
+
+# The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
+# directories that are symbolic links (a Unix file system feature) are excluded
+# from the input.
+# The default value is: NO.
+
+EXCLUDE_SYMLINKS       = NO
+
+# If the value of the INPUT tag contains directories, you can use the
+# EXCLUDE_PATTERNS tag to specify one or more wildcard patterns to exclude
+# certain files from those directories.
+#
+# Note that the wildcards are matched against the file with absolute path, so to
+# exclude all test directories for example use the pattern */test/*
+
+EXCLUDE_PATTERNS       = */t/*
+
+# The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
+# (namespaces, classes, functions, etc.) that should be excluded from the
+# output. The symbol name can be a fully qualified name, a word, or if the
+# wildcard * is used, a substring. Examples: ANamespace, AClass,
+# ANamespace::AClass, ANamespace::*Test
+#
+# Note that the wildcards are matched against the file with absolute path, so to
+# exclude all test directories use the pattern */test/*
+
+EXCLUDE_SYMBOLS        =
+
+# The EXAMPLE_PATH tag can be used to specify one or more files or directories
+# that contain example code fragments that are included (see the \include
+# command).
+
+EXAMPLE_PATH           =
+
+# If the value of the EXAMPLE_PATH tag contains directories, you can use the
+# EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp and
+# *.h) to filter out the source-files in the directories. If left blank all
+# files are included.
+
+EXAMPLE_PATTERNS       =
+
+# If the EXAMPLE_RECURSIVE tag is set to YES then subdirectories will be
+# searched for input files to be used with the \include or \dontinclude commands
+# irrespective of the value of the RECURSIVE tag.
+# The default value is: NO.
+
+EXAMPLE_RECURSIVE      = NO
+
+# The IMAGE_PATH tag can be used to specify one or more files or directories
+# that contain images that are to be included in the documentation (see the
+# \image command).
+
+IMAGE_PATH             =
+
+# The INPUT_FILTER tag can be used to specify a program that doxygen should
+# invoke to filter for each input file. Doxygen will invoke the filter program
+# by executing (via popen()) the command:
+#
+# <filter> <input-file>
+#
+# where <filter> is the value of the INPUT_FILTER tag, and <input-file> is the
+# name of an input file. Doxygen will then use the output that the filter
+# program writes to standard output. If FILTER_PATTERNS is specified, this tag
+# will be ignored.
+#
+# Note that the filter must not add or remove lines; it is applied before the
+# code is scanned, but not when the output code is generated. If lines are added
+# or removed, the anchors will not be placed correctly.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# properly processed by doxygen.
+
+INPUT_FILTER           =
+
+# The FILTER_PATTERNS tag can be used to specify filters on a per file pattern
+# basis. Doxygen will compare the file name with each pattern and apply the
+# filter if there is a match. The filters are a list of the form: pattern=filter
+# (like *.cpp=my_cpp_filter). See INPUT_FILTER for further information on how
+# filters are used. If the FILTER_PATTERNS tag is empty or if none of the
+# patterns match the file name, INPUT_FILTER is applied.
+#
+# Note that for custom extensions or not directly supported extensions you also
+# need to set EXTENSION_MAPPING for the extension otherwise the files are not
+# properly processed by doxygen.
+
+FILTER_PATTERNS        =
+
+# If the FILTER_SOURCE_FILES tag is set to YES, the input filter (if set using
+# INPUT_FILTER) will also be used to filter the input files that are used for
+# producing the source files to browse (i.e. when SOURCE_BROWSER is set to YES).
+# The default value is: NO.
+
+FILTER_SOURCE_FILES    = NO
+
+# The FILTER_SOURCE_PATTERNS tag can be used to specify source filters per file
+# pattern. A pattern will override the setting for FILTER_PATTERN (if any) and
+# it is also possible to disable source filtering for a specific pattern using
+# *.ext= (so without naming a filter).
+# This tag requires that the tag FILTER_SOURCE_FILES is set to YES.
+
+FILTER_SOURCE_PATTERNS =
+
+# If the USE_MDFILE_AS_MAINPAGE tag refers to the name of a markdown file that
+# is part of the input, its contents will be placed on the main page
+# (index.html). This can be useful if you have a project on for instance GitHub
+# and want to reuse the introduction page also for the doxygen output.
+
+USE_MDFILE_AS_MAINPAGE =
+
+#---------------------------------------------------------------------------
+# Configuration options related to source browsing
+#---------------------------------------------------------------------------
+
+# If the SOURCE_BROWSER tag is set to YES then a list of source files will be
+# generated. Documented entities will be cross-referenced with these sources.
+#
+# Note: To get rid of all source code in the generated output, make sure that
+# also VERBATIM_HEADERS is set to NO.
+# The default value is: NO.
+
+SOURCE_BROWSER         = NO
+
+# Setting the INLINE_SOURCES tag to YES will include the body of functions,
+# classes and enums directly into the documentation.
+# The default value is: NO.
+
+INLINE_SOURCES         = NO
+
+# Setting the STRIP_CODE_COMMENTS tag to YES will instruct doxygen to hide any
+# special comment blocks from generated source code fragments. Normal C, C++ and
+# Fortran comments will always remain visible.
+# The default value is: YES.
+
+STRIP_CODE_COMMENTS    = YES
+
+# If the REFERENCED_BY_RELATION tag is set to YES then for each documented
+# entity all documented functions referencing it will be listed.
+# The default value is: NO.
+
+REFERENCED_BY_RELATION = @BUILD_DEVEL_DOCS@
+
+# If the REFERENCES_RELATION tag is set to YES then for each documented function
+# all documented entities called/used by that function will be listed.
+# The default value is: NO.
+
+REFERENCES_RELATION    = @BUILD_DEVEL_DOCS@
+
+# If the REFERENCES_LINK_SOURCE tag is set to YES and SOURCE_BROWSER tag is set
+# to YES then the hyperlinks from functions in REFERENCES_RELATION and
+# REFERENCED_BY_RELATION lists will link to the source code. Otherwise they will
+# link to the documentation.
+# The default value is: YES.
+
+REFERENCES_LINK_SOURCE = YES
+
+# If SOURCE_TOOLTIPS is enabled (the default) then hovering a hyperlink in the
+# source code will show a tooltip with additional information such as prototype,
+# brief description and links to the definition and documentation. Since this
+# will make the HTML file larger and loading of large files a bit slower, you
+# can opt to disable this feature.
+# The default value is: YES.
+# This tag requires that the tag SOURCE_BROWSER is set to YES.
+
+SOURCE_TOOLTIPS        = YES
+
+# If the USE_HTAGS tag is set to YES then the references to source code will
+# point to the HTML generated by the htags(1) tool instead of doxygen built-in
+# source browser. The htags tool is part of GNU's global source tagging system
+# (see https://www.gnu.org/software/global/global.html). You will need version
+# 4.8.6 or higher.
+#
+# To use it do the following:
+# - Install the latest version of global
+# - Enable SOURCE_BROWSER and USE_HTAGS in the configuration file
+# - Make sure the INPUT points to the root of the source tree
+# - Run doxygen as normal
+#
+# Doxygen will invoke htags (and that will in turn invoke gtags), so these
+# tools must be available from the command line (i.e. in the search path).
+#
+# The result: instead of the source browser generated by doxygen, the links to
+# source code will now point to the output of htags.
+# The default value is: NO.
+# This tag requires that the tag SOURCE_BROWSER is set to YES.
+
+USE_HTAGS              = NO
+
+# If the VERBATIM_HEADERS tag is set the YES then doxygen will generate a
+# verbatim copy of the header file for each class for which an include is
+# specified. Set to NO to disable this.
+# See also: Section \class.
+# The default value is: YES.
+
+VERBATIM_HEADERS       = YES
+
+# If the CLANG_ASSISTED_PARSING tag is set to YES then doxygen will use the
+# clang parser (see:
+# http://clang.llvm.org/) for more accurate parsing at the cost of reduced
+# performance. This can be particularly helpful with template rich C++ code for
+# which doxygen's built-in parser lacks the necessary type information.
+# Note: The availability of this option depends on whether or not doxygen was
+# generated with the -Duse_libclang=ON option for CMake.
+# The default value is: NO.
+
+CLANG_ASSISTED_PARSING = NO
+
+# If the CLANG_ASSISTED_PARSING tag is set to YES and the CLANG_ADD_INC_PATHS
+# tag is set to YES then doxygen will add the directory of each input to the
+# include path.
+# The default value is: YES.
+# This tag requires that the tag CLANG_ASSISTED_PARSING is set to YES.
+
+CLANG_ADD_INC_PATHS    = YES
+
+# If clang assisted parsing is enabled you can provide the compiler with command
+# line options that you would normally use when invoking the compiler. Note that
+# the include paths will already be set by doxygen for the files and directories
+# specified with INPUT and INCLUDE_PATH.
+# This tag requires that the tag CLANG_ASSISTED_PARSING is set to YES.
+
+CLANG_OPTIONS          =
+
+# If clang assisted parsing is enabled you can provide the clang parser with the
+# path to the directory containing a file called compile_commands.json. This
+# file is the compilation database (see:
+# http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html) containing the
+# options used when the source files were built. This is equivalent to
+# specifying the -p option to a clang tool, such as clang-check. These options
+# will then be passed to the parser. Any options specified with CLANG_OPTIONS
+# will be added as well.
+# Note: The availability of this option depends on whether or not doxygen was
+# generated with the -Duse_libclang=ON option for CMake.
+
+CLANG_DATABASE_PATH    =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the alphabetical class index
+#---------------------------------------------------------------------------
+
+# If the ALPHABETICAL_INDEX tag is set to YES, an alphabetical index of all
+# compounds will be generated. Enable this if the project contains a lot of
+# classes, structs, unions or interfaces.
+# The default value is: YES.
+
+ALPHABETICAL_INDEX     = NO
+
+# In case all classes in a project start with a common prefix, all classes will
+# be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
+# can be used to specify a prefix (or a list of prefixes) that should be ignored
+# while generating the index headers.
+# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
+
+IGNORE_PREFIX          =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the HTML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_HTML tag is set to YES, doxygen will generate HTML output
+# The default value is: YES.
+
+GENERATE_HTML          = YES
+
+# The HTML_OUTPUT tag is used to specify where the HTML docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: html.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_OUTPUT            = html
+
+# The HTML_FILE_EXTENSION tag can be used to specify the file extension for each
+# generated HTML page (for example: .htm, .php, .asp).
+# The default value is: .html.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FILE_EXTENSION    = .html
+
+# The HTML_HEADER tag can be used to specify a user-defined HTML header file for
+# each generated HTML page. If the tag is left blank doxygen will generate a
+# standard header.
+#
+# To get valid HTML the header file that includes any scripts and style sheets
+# that doxygen needs, which is dependent on the configuration options used (e.g.
+# the setting GENERATE_TREEVIEW). It is highly recommended to start with a
+# default header using
+# doxygen -w html new_header.html new_footer.html new_stylesheet.css
+# YourConfigFile
+# and then modify the file new_header.html. See also section "Doxygen usage"
+# for information on how to generate the default header that doxygen normally
+# uses.
+# Note: The header is subject to change so you typically have to regenerate the
+# default header when upgrading to a newer version of doxygen. For a description
+# of the possible markers and block names see the documentation.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_HEADER            =
+
+# The HTML_FOOTER tag can be used to specify a user-defined HTML footer for each
+# generated HTML page. If the tag is left blank doxygen will generate a standard
+# footer. See HTML_HEADER for more information on how to generate a default
+# footer and what special commands can be used inside the footer. See also
+# section "Doxygen usage" for information on how to generate the default footer
+# that doxygen normally uses.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FOOTER            =
+
+# The HTML_STYLESHEET tag can be used to specify a user-defined cascading style
+# sheet that is used by each HTML page. It can be used to fine-tune the look of
+# the HTML output. If left blank doxygen will generate a default style sheet.
+# See also section "Doxygen usage" for information on how to generate the style
+# sheet that doxygen normally uses.
+# Note: It is recommended to use HTML_EXTRA_STYLESHEET instead of this tag, as
+# it is more robust and this tag (HTML_STYLESHEET) will in the future become
+# obsolete.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_STYLESHEET        =
+
+# The HTML_EXTRA_STYLESHEET tag can be used to specify additional user-defined
+# cascading style sheets that are included after the standard style sheets
+# created by doxygen. Using this option one can overrule certain style aspects.
+# This is preferred over using HTML_STYLESHEET since it does not replace the
+# standard style sheet and is therefore more robust against future updates.
+# Doxygen will copy the style sheet files to the output directory.
+# Note: The order of the extra style sheet files is of importance (e.g. the last
+# style sheet in the list overrules the setting of the previous ones in the
+# list). For an example see the documentation.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_EXTRA_STYLESHEET  =
+
+# The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the HTML output directory. Note
+# that these files will be copied to the base HTML output directory. Use the
+# $relpath^ marker in the HTML_HEADER and/or HTML_FOOTER files to load these
+# files. In the HTML_STYLESHEET file, use the file name only. Also note that the
+# files will be copied as-is; there are no commands or markers available.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_EXTRA_FILES       =
+
+# The HTML_COLORSTYLE_HUE tag controls the color of the HTML output. Doxygen
+# will adjust the colors in the style sheet and background images according to
+# this color. Hue is specified as an angle on a color-wheel, see
+# https://en.wikipedia.org/wiki/Hue for more information. For instance the value
+# 0 represents red, 60 is yellow, 120 is green, 180 is cyan, 240 is blue, 300
+# purple, and 360 is red again.
+# Minimum value: 0, maximum value: 359, default value: 220.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_HUE    = 220
+
+# The HTML_COLORSTYLE_SAT tag controls the purity (or saturation) of the colors
+# in the HTML output. For a value of 0 the output will use gray-scales only. A
+# value of 255 will produce the most vivid colors.
+# Minimum value: 0, maximum value: 255, default value: 100.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_SAT    = 100
+
+# The HTML_COLORSTYLE_GAMMA tag controls the gamma correction applied to the
+# luminance component of the colors in the HTML output. Values below 100
+# gradually make the output lighter, whereas values above 100 make the output
+# darker. The value divided by 100 is the actual gamma applied, so 80 represents
+# a gamma of 0.8, The value 220 represents a gamma of 2.2, and 100 does not
+# change the gamma.
+# Minimum value: 40, maximum value: 240, default value: 80.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_COLORSTYLE_GAMMA  = 80
+
+# If the HTML_TIMESTAMP tag is set to YES then the footer of each generated HTML
+# page will contain the date and time when the page was generated. Setting this
+# to YES can help to show when doxygen was last run and thus if the
+# documentation is up to date.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_TIMESTAMP         = NO
+
+# If the HTML_DYNAMIC_MENUS tag is set to YES then the generated HTML
+# documentation will contain a main index with vertical navigation menus that
+# are dynamically created via JavaScript. If disabled, the navigation index will
+# consists of multiple levels of tabs that are statically embedded in every HTML
+# page. Disable this option to support browsers that do not have JavaScript,
+# like the Qt help browser.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_DYNAMIC_MENUS     = YES
+
+# If the HTML_DYNAMIC_SECTIONS tag is set to YES then the generated HTML
+# documentation will contain sections that can be hidden and shown after the
+# page has loaded.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_DYNAMIC_SECTIONS  = NO
+
+# With HTML_INDEX_NUM_ENTRIES one can control the preferred number of entries
+# shown in the various tree structured indices initially; the user can expand
+# and collapse entries dynamically later on. Doxygen will expand the tree to
+# such a level that at most the specified number of entries are visible (unless
+# a fully collapsed tree already exceeds this amount). So setting the number of
+# entries 1 will produce a full collapsed tree by default. 0 is a special value
+# representing an infinite number of entries and will result in a full expanded
+# tree by default.
+# Minimum value: 0, maximum value: 9999, default value: 100.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_INDEX_NUM_ENTRIES = 100
+
+# If the GENERATE_DOCSET tag is set to YES, additional index files will be
+# generated that can be used as input for Apple's Xcode 3 integrated development
+# environment (see:
+# https://developer.apple.com/xcode/), introduced with OSX 10.5 (Leopard). To
+# create a documentation set, doxygen will generate a Makefile in the HTML
+# output directory. Running make will produce the docset in that directory and
+# running make install will install the docset in
+# ~/Library/Developer/Shared/Documentation/DocSets so that Xcode will find it at
+# startup. See https://developer.apple.com/library/archive/featuredarticles/Doxy
+# genXcode/_index.html for more information.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_DOCSET        = NO
+
+# This tag determines the name of the docset feed. A documentation feed provides
+# an umbrella under which multiple documentation sets from a single provider
+# (such as a company or product suite) can be grouped.
+# The default value is: Doxygen generated docs.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_FEEDNAME        = "Doxygen generated docs"
+
+# This tag determines the URL of the docset feed. A documentation feed provides
+# an umbrella under which multiple documentation sets from a single provider
+# (such as a company or product suite) can be grouped.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_FEEDURL         =
+
+# This tag specifies a string that should uniquely identify the documentation
+# set bundle. This should be a reverse domain-name style string, e.g.
+# com.mycompany.MyDocSet. Doxygen will append .docset to the name.
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_BUNDLE_ID       = org.doxygen.Project
+
+# The DOCSET_PUBLISHER_ID tag specifies a string that should uniquely identify
+# the documentation publisher. This should be a reverse domain-name style
+# string, e.g. com.mycompany.MyDocSet.documentation.
+# The default value is: org.doxygen.Publisher.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_PUBLISHER_ID    = org.doxygen.Publisher
+
+# The DOCSET_PUBLISHER_NAME tag identifies the documentation publisher.
+# The default value is: Publisher.
+# This tag requires that the tag GENERATE_DOCSET is set to YES.
+
+DOCSET_PUBLISHER_NAME  = Publisher
+
+# If the GENERATE_HTMLHELP tag is set to YES then doxygen generates three
+# additional HTML index files: index.hhp, index.hhc, and index.hhk. The
+# index.hhp is a project file that can be read by Microsoft's HTML Help Workshop
+# on Windows. In the beginning of 2021 Microsoft took the original page, with
+# a.o. the download links, offline the HTML help workshop was already many years
+# in maintenance mode). You can download the HTML help workshop from the web
+# archives at Installation executable (see:
+# http://web.archive.org/web/20160201063255/http://download.microsoft.com/downlo
+# ad/0/A/9/0A939EF6-E31C-430F-A3DF-DFAE7960D564/htmlhelp.exe).
+#
+# The HTML Help Workshop contains a compiler that can convert all HTML output
+# generated by doxygen into a single compiled HTML file (.chm). Compiled HTML
+# files are now used as the Windows 98 help format, and will replace the old
+# Windows help format (.hlp) on all Windows platforms in the future. Compressed
+# HTML files also contain an index, a table of contents, and you can search for
+# words in the documentation. The HTML workshop also contains a viewer for
+# compressed HTML files.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_HTMLHELP      = NO
+
+# The CHM_FILE tag can be used to specify the file name of the resulting .chm
+# file. You can add a path in front of the file if the result should not be
+# written to the html output directory.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+CHM_FILE               =
+
+# The HHC_LOCATION tag can be used to specify the location (absolute path
+# including file name) of the HTML help compiler (hhc.exe). If non-empty,
+# doxygen will try to run the HTML help compiler on the generated index.hhp.
+# The file has to be specified with full path.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+HHC_LOCATION           =
+
+# The GENERATE_CHI flag controls if a separate .chi index file is generated
+# (YES) or that it should be included in the main .chm file (NO).
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+GENERATE_CHI           = NO
+
+# The CHM_INDEX_ENCODING is used to encode HtmlHelp index (hhk), content (hhc)
+# and project file content.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+CHM_INDEX_ENCODING     =
+
+# The BINARY_TOC flag controls whether a binary table of contents is generated
+# (YES) or a normal table of contents (NO) in the .chm file. Furthermore it
+# enables the Previous and Next buttons.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+BINARY_TOC             = NO
+
+# The TOC_EXPAND flag can be set to YES to add extra items for group members to
+# the table of contents of the HTML help documentation and to the tree view.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTMLHELP is set to YES.
+
+TOC_EXPAND             = NO
+
+# If the GENERATE_QHP tag is set to YES and both QHP_NAMESPACE and
+# QHP_VIRTUAL_FOLDER are set, an additional index file will be generated that
+# can be used as input for Qt's qhelpgenerator to generate a Qt Compressed Help
+# (.qch) of the generated HTML documentation.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_QHP           = NO
+
+# If the QHG_LOCATION tag is specified, the QCH_FILE tag can be used to specify
+# the file name of the resulting .qch file. The path specified is relative to
+# the HTML output folder.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QCH_FILE               =
+
+# The QHP_NAMESPACE tag specifies the namespace to use when generating Qt Help
+# Project output. For more information please see Qt Help Project / Namespace
+# (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#namespace).
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_NAMESPACE          =
+
+# The QHP_VIRTUAL_FOLDER tag specifies the namespace to use when generating Qt
+# Help Project output. For more information please see Qt Help Project / Virtual
+# Folders (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#virtual-folders).
+# The default value is: doc.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_VIRTUAL_FOLDER     = doc
+
+# If the QHP_CUST_FILTER_NAME tag is set, it specifies the name of a custom
+# filter to add. For more information please see Qt Help Project / Custom
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_CUST_FILTER_NAME   =
+
+# The QHP_CUST_FILTER_ATTRS tag specifies the list of the attributes of the
+# custom filter to add. For more information please see Qt Help Project / Custom
+# Filters (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#custom-filters).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_CUST_FILTER_ATTRS  =
+
+# The QHP_SECT_FILTER_ATTRS tag specifies the list of the attributes this
+# project's filter section matches. Qt Help Project / Filter Attributes (see:
+# https://doc.qt.io/archives/qt-4.8/qthelpproject.html#filter-attributes).
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHP_SECT_FILTER_ATTRS  =
+
+# The QHG_LOCATION tag can be used to specify the location (absolute path
+# including file name) of Qt's qhelpgenerator. If non-empty doxygen will try to
+# run qhelpgenerator on the generated .qhp file.
+# This tag requires that the tag GENERATE_QHP is set to YES.
+
+QHG_LOCATION           =
+
+# If the GENERATE_ECLIPSEHELP tag is set to YES, additional index files will be
+# generated, together with the HTML files, they form an Eclipse help plugin. To
+# install this plugin and make it available under the help contents menu in
+# Eclipse, the contents of the directory containing the HTML and XML files needs
+# to be copied into the plugins directory of eclipse. The name of the directory
+# within the plugins directory should be the same as the ECLIPSE_DOC_ID value.
+# After copying Eclipse needs to be restarted before the help appears.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_ECLIPSEHELP   = NO
+
+# A unique identifier for the Eclipse help plugin. When installing the plugin
+# the directory name containing the HTML and XML files should also have this
+# name. Each documentation set should have its own identifier.
+# The default value is: org.doxygen.Project.
+# This tag requires that the tag GENERATE_ECLIPSEHELP is set to YES.
+
+ECLIPSE_DOC_ID         = org.doxygen.Project
+
+# If you want full control over the layout of the generated HTML pages it might
+# be necessary to disable the index and replace it with your own. The
+# DISABLE_INDEX tag can be used to turn on/off the condensed index (tabs) at top
+# of each HTML page. A value of NO enables the index and the value YES disables
+# it. Since the tabs in the index contain the same information as the navigation
+# tree, you can set this option to YES if you also set GENERATE_TREEVIEW to YES.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+DISABLE_INDEX          = NO
+
+# The GENERATE_TREEVIEW tag is used to specify whether a tree-like index
+# structure should be generated to display hierarchical information. If the tag
+# value is set to YES, a side panel will be generated containing a tree-like
+# index structure (just like the one that is generated for HTML Help). For this
+# to work a browser that supports JavaScript, DHTML, CSS and frames is required
+# (i.e. any modern browser). Windows users are probably better off using the
+# HTML help feature. Via custom style sheets (see HTML_EXTRA_STYLESHEET) one can
+# further fine tune the look of the index (see "Fine-tuning the output"). As an
+# example, the default style sheet generated by doxygen has an example that
+# shows how to put an image at the root of the tree instead of the PROJECT_NAME.
+# Since the tree basically has the same information as the tab index, you could
+# consider setting DISABLE_INDEX to YES when enabling this option.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+GENERATE_TREEVIEW      = NO
+
+# When both GENERATE_TREEVIEW and DISABLE_INDEX are set to YES, then the
+# FULL_SIDEBAR option determines if the side bar is limited to only the treeview
+# area (value NO) or if it should extend to the full height of the window (value
+# YES). Setting this to YES gives a layout similar to
+# https://docs.readthedocs.io with more room for contents, but less room for the
+# project logo, title, and description. If either GENERATE_TREEVIEW or
+# DISABLE_INDEX is set to NO, this option has no effect.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FULL_SIDEBAR           = NO
+
+# The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values that
+# doxygen will group on one line in the generated HTML documentation.
+#
+# Note that a value of 0 will completely suppress the enum values from appearing
+# in the overview section.
+# Minimum value: 0, maximum value: 20, default value: 4.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+ENUM_VALUES_PER_LINE   = 4
+
+# If the treeview is enabled (see GENERATE_TREEVIEW) then this tag can be used
+# to set the initial width (in pixels) of the frame in which the tree is shown.
+# Minimum value: 0, maximum value: 1500, default value: 250.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+TREEVIEW_WIDTH         = 250
+
+# If the EXT_LINKS_IN_WINDOW option is set to YES, doxygen will open links to
+# external symbols imported via tag files in a separate window.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+EXT_LINKS_IN_WINDOW    = NO
+
+# If the OBFUSCATE_EMAILS tag is set to YES, doxygen will obfuscate email
+# addresses.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+OBFUSCATE_EMAILS       = YES
+
+# If the HTML_FORMULA_FORMAT option is set to svg, doxygen will use the pdf2svg
+# tool (see https://github.com/dawbarton/pdf2svg) or inkscape (see
+# https://inkscape.org) to generate formulas as SVG images instead of PNGs for
+# the HTML output. These images will generally look nicer at scaled resolutions.
+# Possible values are: png (the default) and svg (looks nicer but requires the
+# pdf2svg or inkscape tool).
+# The default value is: png.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+HTML_FORMULA_FORMAT    = png
+
+# Use this tag to change the font size of LaTeX formulas included as images in
+# the HTML documentation. When you change the font size after a successful
+# doxygen run you need to manually remove any form_*.png images from the HTML
+# output directory to force them to be regenerated.
+# Minimum value: 8, maximum value: 50, default value: 10.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_FONTSIZE       = 10
+
+# Use the FORMULA_TRANSPARENT tag to determine whether or not the images
+# generated for formulas are transparent PNGs. Transparent PNGs are not
+# supported properly for IE 6.0, but are supported on all modern browsers.
+#
+# Note that when changing this option you need to delete any form_*.png files in
+# the HTML output directory before the changes have effect.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FORMULA_TRANSPARENT    = YES
+
+# The FORMULA_MACROFILE can contain LaTeX \newcommand and \renewcommand commands
+# to create new LaTeX commands to be used in formulas as building blocks. See
+# the section "Including formulas" for details.
+
+FORMULA_MACROFILE      =
+
+# Enable the USE_MATHJAX option to render LaTeX formulas using MathJax (see
+# https://www.mathjax.org) which uses client side JavaScript for the rendering
+# instead of using pre-rendered bitmaps. Use this if you do not have LaTeX
+# installed or if you want to formulas look prettier in the HTML output. When
+# enabled you may also need to install MathJax separately and configure the path
+# to it using the MATHJAX_RELPATH option.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+USE_MATHJAX            = NO
+
+# With MATHJAX_VERSION it is possible to specify the MathJax version to be used.
+# Note that the different versions of MathJax have different requirements with
+# regards to the different settings, so it is possible that also other MathJax
+# settings have to be changed when switching between the different MathJax
+# versions.
+# Possible values are: MathJax_2 and MathJax_3.
+# The default value is: MathJax_2.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_VERSION        = MathJax_2
+
+# When MathJax is enabled you can set the default output format to be used for
+# the MathJax output. For more details about the output format see MathJax
+# version 2 (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) and MathJax version 3
+# (see:
+# http://docs.mathjax.org/en/latest/web/components/output.html).
+# Possible values are: HTML-CSS (which is slower, but has the best
+# compatibility. This is the name for Mathjax version 2, for MathJax version 3
+# this will be translated into chtml), NativeMML (i.e. MathML. Only supported
+# for NathJax 2. For MathJax version 3 chtml will be used instead.), chtml (This
+# is the name for Mathjax version 3, for MathJax version 2 this will be
+# translated into HTML-CSS) and SVG.
+# The default value is: HTML-CSS.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_FORMAT         = HTML-CSS
+
+# When MathJax is enabled you need to specify the location relative to the HTML
+# output directory using the MATHJAX_RELPATH option. The destination directory
+# should contain the MathJax.js script. For instance, if the mathjax directory
+# is located at the same level as the HTML output directory, then
+# MATHJAX_RELPATH should be ../mathjax. The default value points to the MathJax
+# Content Delivery Network so you can quickly see the result without installing
+# MathJax. However, it is strongly recommended to install a local copy of
+# MathJax from https://www.mathjax.org before deployment. The default value is:
+# - in case of MathJax version 2: https://cdn.jsdelivr.net/npm/mathjax@2
+# - in case of MathJax version 3: https://cdn.jsdelivr.net/npm/mathjax@3
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_RELPATH        = http://cdn.mathjax.org/mathjax/latest
+
+# The MATHJAX_EXTENSIONS tag can be used to specify one or more MathJax
+# extension names that should be enabled during MathJax rendering. For example
+# for MathJax version 2 (see
+# https://docs.mathjax.org/en/v2.7-latest/tex.html#tex-and-latex-extensions):
+# MATHJAX_EXTENSIONS = TeX/AMSmath TeX/AMSsymbols
+# For example for MathJax version 3 (see
+# http://docs.mathjax.org/en/latest/input/tex/extensions/index.html):
+# MATHJAX_EXTENSIONS = ams
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_EXTENSIONS     =
+
+# The MATHJAX_CODEFILE tag can be used to specify a file with javascript pieces
+# of code that will be used on startup of the MathJax code. See the MathJax site
+# (see:
+# http://docs.mathjax.org/en/v2.7-latest/output.html) for more details. For an
+# example see the documentation.
+# This tag requires that the tag USE_MATHJAX is set to YES.
+
+MATHJAX_CODEFILE       =
+
+# When the SEARCHENGINE tag is enabled doxygen will generate a search box for
+# the HTML output. The underlying search engine uses javascript and DHTML and
+# should work on any modern browser. Note that when using HTML help
+# (GENERATE_HTMLHELP), Qt help (GENERATE_QHP), or docsets (GENERATE_DOCSET)
+# there is already a search function so this one should typically be disabled.
+# For large projects the javascript based search engine can be slow, then
+# enabling SERVER_BASED_SEARCH may provide a better solution. It is possible to
+# search using the keyboard; to jump to the search box use <access key> + S
+# (what the <access key> is depends on the OS and browser, but it is typically
+# <CTRL>, <ALT>/<option>, or both). Inside the search box use the <cursor down
+# key> to jump into the search results window, the results can be navigated
+# using the <cursor keys>. Press <Enter> to select an item or <escape> to cancel
+# the search. The filter options can be selected when the cursor is inside the
+# search box by pressing <Shift>+<cursor down>. Also here use the <cursor keys>
+# to select a filter and <Enter> or <escape> to activate or cancel the filter
+# option.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+SEARCHENGINE           = YES
+
+# When the SERVER_BASED_SEARCH tag is enabled the search engine will be
+# implemented using a web server instead of a web client using JavaScript. There
+# are two flavors of web server based searching depending on the EXTERNAL_SEARCH
+# setting. When disabled, doxygen will generate a PHP script for searching and
+# an index file used by the script. When EXTERNAL_SEARCH is enabled the indexing
+# and searching needs to be provided by external tools. See the section
+# "External Indexing and Searching" for details.
+# The default value is: NO.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SERVER_BASED_SEARCH    = NO
+
+# When EXTERNAL_SEARCH tag is enabled doxygen will no longer generate the PHP
+# script for searching. Instead the search results are written to an XML file
+# which needs to be processed by an external indexer. Doxygen will invoke an
+# external search engine pointed to by the SEARCHENGINE_URL option to obtain the
+# search results.
+#
+# Doxygen ships with an example indexer (doxyindexer) and search engine
+# (doxysearch.cgi) which are based on the open source search engine library
+# Xapian (see:
+# https://xapian.org/).
+#
+# See the section "External Indexing and Searching" for details.
+# The default value is: NO.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTERNAL_SEARCH        = NO
+
+# The SEARCHENGINE_URL should point to a search engine hosted by a web server
+# which will return the search results when EXTERNAL_SEARCH is enabled.
+#
+# Doxygen ships with an example indexer (doxyindexer) and search engine
+# (doxysearch.cgi) which are based on the open source search engine library
+# Xapian (see:
+# https://xapian.org/). See the section "External Indexing and Searching" for
+# details.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SEARCHENGINE_URL       =
+
+# When SERVER_BASED_SEARCH and EXTERNAL_SEARCH are both enabled the unindexed
+# search data is written to a file for indexing by an external tool. With the
+# SEARCHDATA_FILE tag the name of this file can be specified.
+# The default file is: searchdata.xml.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+SEARCHDATA_FILE        = searchdata.xml
+
+# When SERVER_BASED_SEARCH and EXTERNAL_SEARCH are both enabled the
+# EXTERNAL_SEARCH_ID tag can be used as an identifier for the project. This is
+# useful in combination with EXTRA_SEARCH_MAPPINGS to search through multiple
+# projects and redirect the results back to the right project.
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTERNAL_SEARCH_ID     =
+
+# The EXTRA_SEARCH_MAPPINGS tag can be used to enable searching through doxygen
+# projects other than the one defined by this configuration file, but that are
+# all added to the same external search index. Each project needs to have a
+# unique id set via EXTERNAL_SEARCH_ID. The search mapping then maps the id of
+# to a relative location where the documentation can be found. The format is:
+# EXTRA_SEARCH_MAPPINGS = tagname1=loc1 tagname2=loc2 ...
+# This tag requires that the tag SEARCHENGINE is set to YES.
+
+EXTRA_SEARCH_MAPPINGS  =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the LaTeX output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_LATEX tag is set to YES, doxygen will generate LaTeX output.
+# The default value is: YES.
+
+GENERATE_LATEX         = NO
+
+# The LATEX_OUTPUT tag is used to specify where the LaTeX docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: latex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_OUTPUT           = latex
+
+# The LATEX_CMD_NAME tag can be used to specify the LaTeX command name to be
+# invoked.
+#
+# Note that when not enabling USE_PDFLATEX the default is latex when enabling
+# USE_PDFLATEX the default is pdflatex and when in the later case latex is
+# chosen this is overwritten by pdflatex. For specific output languages the
+# default can have been set differently, this depends on the implementation of
+# the output language.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_CMD_NAME         = latex
+
+# The MAKEINDEX_CMD_NAME tag can be used to specify the command name to generate
+# index for LaTeX.
+# Note: This tag is used in the Makefile / make.bat.
+# See also: LATEX_MAKEINDEX_CMD for the part in the generated output file
+# (.tex).
+# The default file is: makeindex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+MAKEINDEX_CMD_NAME     = makeindex
+
+# The LATEX_MAKEINDEX_CMD tag can be used to specify the command name to
+# generate index for LaTeX. In case there is no backslash (\) as first character
+# it will be automatically added in the LaTeX code.
+# Note: This tag is used in the generated output file (.tex).
+# See also: MAKEINDEX_CMD_NAME for the part in the Makefile / make.bat.
+# The default value is: makeindex.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_MAKEINDEX_CMD    = makeindex
+
+# If the COMPACT_LATEX tag is set to YES, doxygen generates more compact LaTeX
+# documents. This may be useful for small projects and may help to save some
+# trees in general.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+COMPACT_LATEX          = NO
+
+# The PAPER_TYPE tag can be used to set the paper type that is used by the
+# printer.
+# Possible values are: a4 (210 x 297 mm), letter (8.5 x 11 inches), legal (8.5 x
+# 14 inches) and executive (7.25 x 10.5 inches).
+# The default value is: a4.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+PAPER_TYPE             = a4
+
+# The EXTRA_PACKAGES tag can be used to specify one or more LaTeX package names
+# that should be included in the LaTeX output. The package can be specified just
+# by its name or with the correct syntax as to be used with the LaTeX
+# \usepackage command. To get the times font for instance you can specify :
+# EXTRA_PACKAGES=times or EXTRA_PACKAGES={times}
+# To use the option intlimits with the amsmath package you can specify:
+# EXTRA_PACKAGES=[intlimits]{amsmath}
+# If left blank no extra packages will be included.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+EXTRA_PACKAGES         =
+
+# The LATEX_HEADER tag can be used to specify a user-defined LaTeX header for
+# the generated LaTeX document. The header should contain everything until the
+# first chapter. If it is left blank doxygen will generate a standard header. It
+# is highly recommended to start with a default header using
+# doxygen -w latex new_header.tex new_footer.tex new_stylesheet.sty
+# and then modify the file new_header.tex. See also section "Doxygen usage" for
+# information on how to generate the default header that doxygen normally uses.
+#
+# Note: Only use a user-defined header if you know what you are doing!
+# Note: The header is subject to change so you typically have to regenerate the
+# default header when upgrading to a newer version of doxygen. The following
+# commands have a special meaning inside the header (and footer): For a
+# description of the possible markers and block names see the documentation.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_HEADER           =
+
+# The LATEX_FOOTER tag can be used to specify a user-defined LaTeX footer for
+# the generated LaTeX document. The footer should contain everything after the
+# last chapter. If it is left blank doxygen will generate a standard footer. See
+# LATEX_HEADER for more information on how to generate a default footer and what
+# special commands can be used inside the footer. See also section "Doxygen
+# usage" for information on how to generate the default footer that doxygen
+# normally uses. Note: Only use a user-defined footer if you know what you are
+# doing!
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_FOOTER           =
+
+# The LATEX_EXTRA_STYLESHEET tag can be used to specify additional user-defined
+# LaTeX style sheets that are included after the standard style sheets created
+# by doxygen. Using this option one can overrule certain style aspects. Doxygen
+# will copy the style sheet files to the output directory.
+# Note: The order of the extra style sheet files is of importance (e.g. the last
+# style sheet in the list overrules the setting of the previous ones in the
+# list).
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EXTRA_STYLESHEET =
+
+# The LATEX_EXTRA_FILES tag can be used to specify one or more extra images or
+# other source files which should be copied to the LATEX_OUTPUT output
+# directory. Note that the files will be copied as-is; there are no commands or
+# markers available.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EXTRA_FILES      =
+
+# If the PDF_HYPERLINKS tag is set to YES, the LaTeX that is generated is
+# prepared for conversion to PDF (using ps2pdf or pdflatex). The PDF file will
+# contain links (just like the HTML output) instead of page references. This
+# makes the output suitable for online browsing using a PDF viewer.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+PDF_HYPERLINKS         = YES
+
+# If the USE_PDFLATEX tag is set to YES, doxygen will use the engine as
+# specified with LATEX_CMD_NAME to generate the PDF file directly from the LaTeX
+# files. Set this option to YES, to get a higher quality PDF documentation.
+#
+# See also section LATEX_CMD_NAME for selecting the engine.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+USE_PDFLATEX           = YES
+
+# If the LATEX_BATCHMODE tag is set to YES, doxygen will add the \batchmode
+# command to the generated LaTeX files. This will instruct LaTeX to keep running
+# if errors occur, instead of asking the user for help.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_BATCHMODE        = NO
+
+# If the LATEX_HIDE_INDICES tag is set to YES then doxygen will not include the
+# index chapters (such as File Index, Compound Index, etc.) in the output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_HIDE_INDICES     = NO
+
+# The LATEX_BIB_STYLE tag can be used to specify the style to use for the
+# bibliography, e.g. plainnat, or ieeetr. See
+# https://en.wikipedia.org/wiki/BibTeX and \cite for more info.
+# The default value is: plain.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_BIB_STYLE        = plain
+
+# If the LATEX_TIMESTAMP tag is set to YES then the footer of each generated
+# page will contain the date and time when the page was generated. Setting this
+# to NO can help when comparing the output of multiple runs.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_TIMESTAMP        = NO
+
+# The LATEX_EMOJI_DIRECTORY tag is used to specify the (relative or absolute)
+# path from which the emoji images will be read. If a relative path is entered,
+# it will be relative to the LATEX_OUTPUT directory. If left blank the
+# LATEX_OUTPUT directory will be used.
+# This tag requires that the tag GENERATE_LATEX is set to YES.
+
+LATEX_EMOJI_DIRECTORY  =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the RTF output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_RTF tag is set to YES, doxygen will generate RTF output. The
+# RTF output is optimized for Word 97 and may not look too pretty with other RTF
+# readers/editors.
+# The default value is: NO.
+
+GENERATE_RTF           = NO
+
+# The RTF_OUTPUT tag is used to specify where the RTF docs will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: rtf.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_OUTPUT             = rtf
+
+# If the COMPACT_RTF tag is set to YES, doxygen generates more compact RTF
+# documents. This may be useful for small projects and may help to save some
+# trees in general.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+COMPACT_RTF            = NO
+
+# If the RTF_HYPERLINKS tag is set to YES, the RTF that is generated will
+# contain hyperlink fields. The RTF file will contain links (just like the HTML
+# output) instead of page references. This makes the output suitable for online
+# browsing using Word or some other Word compatible readers that support those
+# fields.
+#
+# Note: WordPad (write) and others do not support links.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_HYPERLINKS         = NO
+
+# Load stylesheet definitions from file. Syntax is similar to doxygen's
+# configuration file, i.e. a series of assignments. You only have to provide
+# replacements, missing definitions are set to their default value.
+#
+# See also section "Doxygen usage" for information on how to generate the
+# default style sheet that doxygen normally uses.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_STYLESHEET_FILE    =
+
+# Set optional variables used in the generation of an RTF document. Syntax is
+# similar to doxygen's configuration file. A template extensions file can be
+# generated using doxygen -e rtf extensionFile.
+# This tag requires that the tag GENERATE_RTF is set to YES.
+
+RTF_EXTENSIONS_FILE    =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the man page output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_MAN tag is set to YES, doxygen will generate man pages for
+# classes and files.
+# The default value is: NO.
+
+GENERATE_MAN           = NO
+
+# The MAN_OUTPUT tag is used to specify where the man pages will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it. A directory man3 will be created inside the directory specified by
+# MAN_OUTPUT.
+# The default directory is: man.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_OUTPUT             = man
+
+# The MAN_EXTENSION tag determines the extension that is added to the generated
+# man pages. In case the manual section does not start with a number, the number
+# 3 is prepended. The dot (.) at the beginning of the MAN_EXTENSION tag is
+# optional.
+# The default value is: .3.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_EXTENSION          = .3
+
+# The MAN_SUBDIR tag determines the name of the directory created within
+# MAN_OUTPUT in which the man pages are placed. If defaults to man followed by
+# MAN_EXTENSION with the initial . removed.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_SUBDIR             =
+
+# If the MAN_LINKS tag is set to YES and doxygen generates man output, then it
+# will generate one additional man file for each entity documented in the real
+# man page(s). These additional files only source the real man page, but without
+# them the man command would be unable to find the correct page.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_MAN is set to YES.
+
+MAN_LINKS              = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the XML output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_XML tag is set to YES, doxygen will generate an XML file that
+# captures the structure of the code including all documentation.
+# The default value is: NO.
+
+GENERATE_XML           = NO
+
+# The XML_OUTPUT tag is used to specify where the XML pages will be put. If a
+# relative path is entered the value of OUTPUT_DIRECTORY will be put in front of
+# it.
+# The default directory is: xml.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_OUTPUT             = xml
+
+# If the XML_PROGRAMLISTING tag is set to YES, doxygen will dump the program
+# listings (including syntax highlighting and cross-referencing information) to
+# the XML output. Note that enabling this will significantly increase the size
+# of the XML output.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_PROGRAMLISTING     = YES
+
+# If the XML_NS_MEMB_FILE_SCOPE tag is set to YES, doxygen will include
+# namespace members in file scope as well, matching the HTML output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_XML is set to YES.
+
+XML_NS_MEMB_FILE_SCOPE = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the DOCBOOK output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_DOCBOOK tag is set to YES, doxygen will generate Docbook files
+# that can be used to generate PDF.
+# The default value is: NO.
+
+GENERATE_DOCBOOK       = NO
+
+# The DOCBOOK_OUTPUT tag is used to specify where the Docbook pages will be put.
+# If a relative path is entered the value of OUTPUT_DIRECTORY will be put in
+# front of it.
+# The default directory is: docbook.
+# This tag requires that the tag GENERATE_DOCBOOK is set to YES.
+
+DOCBOOK_OUTPUT         = docbook
+
+#---------------------------------------------------------------------------
+# Configuration options for the AutoGen Definitions output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_AUTOGEN_DEF tag is set to YES, doxygen will generate an
+# AutoGen Definitions (see http://autogen.sourceforge.net/) file that captures
+# the structure of the code including all documentation. Note that this feature
+# is still experimental and incomplete at the moment.
+# The default value is: NO.
+
+GENERATE_AUTOGEN_DEF   = NO
+
+#---------------------------------------------------------------------------
+# Configuration options related to the Perl module output
+#---------------------------------------------------------------------------
+
+# If the GENERATE_PERLMOD tag is set to YES, doxygen will generate a Perl module
+# file that captures the structure of the code including all documentation.
+#
+# Note that this feature is still experimental and incomplete at the moment.
+# The default value is: NO.
+
+GENERATE_PERLMOD       = NO
+
+# If the PERLMOD_LATEX tag is set to YES, doxygen will generate the necessary
+# Makefile rules, Perl scripts and LaTeX code to be able to generate PDF and DVI
+# output from the Perl module output.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_LATEX          = NO
+
+# If the PERLMOD_PRETTY tag is set to YES, the Perl module output will be nicely
+# formatted so it can be parsed by a human reader. This is useful if you want to
+# understand what is going on. On the other hand, if this tag is set to NO, the
+# size of the Perl module output will be much smaller and Perl will parse it
+# just the same.
+# The default value is: YES.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_PRETTY         = YES
+
+# The names of the make variables in the generated doxyrules.make file are
+# prefixed with the string contained in PERLMOD_MAKEVAR_PREFIX. This is useful
+# so different doxyrules.make files included by the same Makefile don't
+# overwrite each other's variables.
+# This tag requires that the tag GENERATE_PERLMOD is set to YES.
+
+PERLMOD_MAKEVAR_PREFIX =
+
+#---------------------------------------------------------------------------
+# Configuration options related to the preprocessor
+#---------------------------------------------------------------------------
+
+# If the ENABLE_PREPROCESSING tag is set to YES, doxygen will evaluate all
+# C-preprocessor directives found in the sources and include files.
+# The default value is: YES.
+
+ENABLE_PREPROCESSING   = YES
+
+# If the MACRO_EXPANSION tag is set to YES, doxygen will expand all macro names
+# in the source code. If set to NO, only conditional compilation will be
+# performed. Macro expansion can be done in a controlled way by setting
+# EXPAND_ONLY_PREDEF to YES.
+# The default value is: NO.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+MACRO_EXPANSION        = NO
+
+# If the EXPAND_ONLY_PREDEF and MACRO_EXPANSION tags are both set to YES then
+# the macro expansion is limited to the macros specified with the PREDEFINED and
+# EXPAND_AS_DEFINED tags.
+# The default value is: NO.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+EXPAND_ONLY_PREDEF     = NO
+
+# If the SEARCH_INCLUDES tag is set to YES, the include files in the
+# INCLUDE_PATH will be searched if a #include is found.
+# The default value is: YES.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+SEARCH_INCLUDES        = YES
+
+# The INCLUDE_PATH tag can be used to specify one or more directories that
+# contain include files that are not input files but should be processed by the
+# preprocessor. Note that the INCLUDE_PATH is not recursive, so the setting of
+# RECURSIVE has no effect here.
+# This tag requires that the tag SEARCH_INCLUDES is set to YES.
+
+INCLUDE_PATH           =
+
+# You can use the INCLUDE_FILE_PATTERNS tag to specify one or more wildcard
+# patterns (like *.h and *.hpp) to filter out the header-files in the
+# directories. If left blank, the patterns specified with FILE_PATTERNS will be
+# used.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+INCLUDE_FILE_PATTERNS  =
+
+# The PREDEFINED tag can be used to specify one or more macro names that are
+# defined before the preprocessor is started (similar to the -D option of e.g.
+# gcc). The argument of the tag is a list of macros of the form: name or
+# name=definition (no spaces). If the definition and the "=" are omitted, "=1"
+# is assumed. To prevent a macro definition from being undefined via #undef or
+# recursively expanded use the := operator instead of the = operator.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+PREDEFINED             =
+
+# If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this
+# tag can be used to specify a list of macro names that should be expanded. The
+# macro definition that is found in the sources will be used. Use the PREDEFINED
+# tag if you want to use a different macro definition that overrules the
+# definition found in the source code.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+EXPAND_AS_DEFINED      =
+
+# If the SKIP_FUNCTION_MACROS tag is set to YES then doxygen's preprocessor will
+# remove all references to function-like macros that are alone on a line, have
+# an all uppercase name, and do not end with a semicolon. Such function macros
+# are typically used for boiler-plate code, and will confuse the parser if not
+# removed.
+# The default value is: YES.
+# This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
+
+SKIP_FUNCTION_MACROS   = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to external references
+#---------------------------------------------------------------------------
+
+# The TAGFILES tag can be used to specify one or more tag files. For each tag
+# file the location of the external documentation should be added. The format of
+# a tag file without this location is as follows:
+# TAGFILES = file1 file2 ...
+# Adding location for the tag files is done as follows:
+# TAGFILES = file1=loc1 "file2 = loc2" ...
+# where loc1 and loc2 can be relative or absolute paths or URLs. See the
+# section "Linking to external documentation" for more information about the use
+# of tag files.
+# Note: Each tag file must have a unique name (where the name does NOT include
+# the path). If a tag file is not located in the directory in which doxygen is
+# run, you must also specify the path to the tagfile here.
+
+TAGFILES               =
+
+# When a file name is specified after GENERATE_TAGFILE, doxygen will create a
+# tag file that is based on the input files it reads. See section "Linking to
+# external documentation" for more information about the usage of tag files.
+
+GENERATE_TAGFILE       =
+
+# If the ALLEXTERNALS tag is set to YES, all external class will be listed in
+# the class index. If set to NO, only the inherited external classes will be
+# listed.
+# The default value is: NO.
+
+ALLEXTERNALS           = NO
+
+# If the EXTERNAL_GROUPS tag is set to YES, all external groups will be listed
+# in the modules index. If set to NO, only the current project's groups will be
+# listed.
+# The default value is: YES.
+
+EXTERNAL_GROUPS        = YES
+
+# If the EXTERNAL_PAGES tag is set to YES, all external pages will be listed in
+# the related pages index. If set to NO, only the current project's pages will
+# be listed.
+# The default value is: YES.
+
+EXTERNAL_PAGES         = YES
+
+#---------------------------------------------------------------------------
+# Configuration options related to the dot tool
+#---------------------------------------------------------------------------
+
+# You can include diagrams made with dia in doxygen documentation. Doxygen will
+# then run dia to produce the diagram and insert it in the documentation. The
+# DIA_PATH tag allows you to specify the directory where the dia binary resides.
+# If left empty dia is assumed to be found in the default search path.
+
+DIA_PATH               =
+
+# If set to YES the inheritance and collaboration graphs will hide inheritance
+# and usage relations if the target is undocumented or is not a class.
+# The default value is: YES.
+
+HIDE_UNDOC_RELATIONS   = YES
+
+# If you set the HAVE_DOT tag to YES then doxygen will assume the dot tool is
+# available from the path. This tool is part of Graphviz (see:
+# http://www.graphviz.org/), a graph visualization toolkit from AT&T and Lucent
+# Bell Labs. The other options in this section have no effect if this option is
+# set to NO
+# The default value is: YES.
+
+HAVE_DOT               = @HAVE_DOT@
+
+# The DOT_NUM_THREADS specifies the number of dot invocations doxygen is allowed
+# to run in parallel. When set to 0 doxygen will base this on the number of
+# processors available in the system. You can set it explicitly to a value
+# larger than 0 to get control over the balance between CPU load and processing
+# speed.
+# Minimum value: 0, maximum value: 32, default value: 0.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_NUM_THREADS        = 0
+
+# When you want a differently looking font in the dot files that doxygen
+# generates you can specify the font name using DOT_FONTNAME. You need to make
+# sure dot is able to find the font, which can be done by putting it in a
+# standard location or by setting the DOTFONTPATH environment variable or by
+# setting DOT_FONTPATH to the directory containing the font.
+# The default value is: Helvetica.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTNAME           =
+
+# The DOT_FONTSIZE tag can be used to set the size (in points) of the font of
+# dot graphs.
+# Minimum value: 4, maximum value: 24, default value: 10.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTSIZE           = 10
+
+# By default doxygen will tell dot to use the default font as specified with
+# DOT_FONTNAME. If you specify a different font using DOT_FONTNAME you can set
+# the path where dot can find it using this tag.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_FONTPATH           =
+
+# If the CLASS_GRAPH tag is set to YES (or GRAPH) then doxygen will generate a
+# graph for each documented class showing the direct and indirect inheritance
+# relations. In case HAVE_DOT is set as well dot will be used to draw the graph,
+# otherwise the built-in generator will be used. If the CLASS_GRAPH tag is set
+# to TEXT the direct and indirect inheritance relations will be shown as texts /
+# links.
+# Possible values are: NO, YES, TEXT and GRAPH.
+# The default value is: YES.
+
+CLASS_GRAPH            = YES
+
+# If the COLLABORATION_GRAPH tag is set to YES then doxygen will generate a
+# graph for each documented class showing the direct and indirect implementation
+# dependencies (inheritance, containment, and class references variables) of the
+# class with other documented classes.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+COLLABORATION_GRAPH    = YES
+
+# If the GROUP_GRAPHS tag is set to YES then doxygen will generate a graph for
+# groups, showing the direct groups dependencies. See also the chapter Grouping
+# in the manual.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GROUP_GRAPHS           = YES
+
+# If the UML_LOOK tag is set to YES, doxygen will generate inheritance and
+# collaboration diagrams in a style similar to the OMG's Unified Modeling
+# Language.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+UML_LOOK               = NO
+
+# If the UML_LOOK tag is enabled, the fields and methods are shown inside the
+# class node. If there are many fields or methods and many nodes the graph may
+# become too big to be useful. The UML_LIMIT_NUM_FIELDS threshold limits the
+# number of items for each type to make the size more manageable. Set this to 0
+# for no limit. Note that the threshold may be exceeded by 50% before the limit
+# is enforced. So when you set the threshold to 10, up to 15 fields may appear,
+# but if the number exceeds 15, the total amount of fields shown is limited to
+# 10.
+# Minimum value: 0, maximum value: 100, default value: 10.
+# This tag requires that the tag UML_LOOK is set to YES.
+
+UML_LIMIT_NUM_FIELDS   = 10
+
+# If the DOT_UML_DETAILS tag is set to NO, doxygen will show attributes and
+# methods without types and arguments in the UML graphs. If the DOT_UML_DETAILS
+# tag is set to YES, doxygen will add type and arguments for attributes and
+# methods in the UML graphs. If the DOT_UML_DETAILS tag is set to NONE, doxygen
+# will not generate fields with class member information in the UML graphs. The
+# class diagrams will look similar to the default class diagrams but using UML
+# notation for the relationships.
+# Possible values are: NO, YES and NONE.
+# The default value is: NO.
+# This tag requires that the tag UML_LOOK is set to YES.
+
+DOT_UML_DETAILS        = NO
+
+# The DOT_WRAP_THRESHOLD tag can be used to set the maximum number of characters
+# to display on a single line. If the actual line length exceeds this threshold
+# significantly it will wrapped across multiple lines. Some heuristics are apply
+# to avoid ugly line breaks.
+# Minimum value: 0, maximum value: 1000, default value: 17.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_WRAP_THRESHOLD     = 17
+
+# If the TEMPLATE_RELATIONS tag is set to YES then the inheritance and
+# collaboration graphs will show the relations between templates and their
+# instances.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+TEMPLATE_RELATIONS     = NO
+
+# If the INCLUDE_GRAPH, ENABLE_PREPROCESSING and SEARCH_INCLUDES tags are set to
+# YES then doxygen will generate a graph for each documented file showing the
+# direct and indirect include dependencies of the file with other documented
+# files.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INCLUDE_GRAPH          = YES
+
+# If the INCLUDED_BY_GRAPH, ENABLE_PREPROCESSING and SEARCH_INCLUDES tags are
+# set to YES then doxygen will generate a graph for each documented file showing
+# the direct and indirect include dependencies of the file with other documented
+# files.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INCLUDED_BY_GRAPH      = YES
+
+# If the CALL_GRAPH tag is set to YES then doxygen will generate a call
+# dependency graph for every global function or class method.
+#
+# Note that enabling this option will significantly increase the time of a run.
+# So in most cases it will be better to enable call graphs for selected
+# functions only using the \callgraph command. Disabling a call graph can be
+# accomplished by means of the command \hidecallgraph.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+CALL_GRAPH             = YES
+
+# If the CALLER_GRAPH tag is set to YES then doxygen will generate a caller
+# dependency graph for every global function or class method.
+#
+# Note that enabling this option will significantly increase the time of a run.
+# So in most cases it will be better to enable caller graphs for selected
+# functions only using the \callergraph command. Disabling a caller graph can be
+# accomplished by means of the command \hidecallergraph.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+CALLER_GRAPH           = YES
+
+# If the GRAPHICAL_HIERARCHY tag is set to YES then doxygen will graphical
+# hierarchy of all classes instead of a textual one.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GRAPHICAL_HIERARCHY    = YES
+
+# If the DIRECTORY_GRAPH tag is set to YES then doxygen will show the
+# dependencies a directory has on other directories in a graphical way. The
+# dependency relations are determined by the #include relations between the
+# files in the directories.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DIRECTORY_GRAPH        = YES
+
+# The DIR_GRAPH_MAX_DEPTH tag can be used to limit the maximum number of levels
+# of child directories generated in directory dependency graphs by dot.
+# Minimum value: 1, maximum value: 25, default value: 1.
+# This tag requires that the tag DIRECTORY_GRAPH is set to YES.
+
+DIR_GRAPH_MAX_DEPTH    = 1
+
+# The DOT_IMAGE_FORMAT tag can be used to set the image format of the images
+# generated by dot. For an explanation of the image formats see the section
+# output formats in the documentation of the dot tool (Graphviz (see:
+# http://www.graphviz.org/)).
+# Note: If you choose svg you need to set HTML_FILE_EXTENSION to xhtml in order
+# to make the SVG files visible in IE 9+ (other browsers do not have this
+# requirement).
+# Possible values are: png, jpg, jpg:cairo, jpg:cairo:gd, jpg:gd, jpg:gd:gd,
+# gif, gif:cairo, gif:cairo:gd, gif:gd, gif:gd:gd, svg, png:gd, png:gd:gd,
+# png:cairo, png:cairo:gd, png:cairo:cairo, png:cairo:gdiplus, png:gdiplus and
+# png:gdiplus:gdiplus.
+# The default value is: png.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_IMAGE_FORMAT       = svg
+
+# If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to
+# enable generation of interactive SVG images that allow zooming and panning.
+#
+# Note that this requires a modern browser other than Internet Explorer. Tested
+# and working are Firefox, Chrome, Safari, and Opera.
+# Note: For IE 9+ you need to set HTML_FILE_EXTENSION to xhtml in order to make
+# the SVG files visible. Older versions of IE do not have SVG support.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+INTERACTIVE_SVG        = NO
+
+# The DOT_PATH tag can be used to specify the path where the dot tool can be
+# found. If left blank, it is assumed the dot tool can be found in the path.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_PATH               =
+
+# The DOTFILE_DIRS tag can be used to specify one or more directories that
+# contain dot files that are included in the documentation (see the \dotfile
+# command).
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOTFILE_DIRS           =
+
+# The MSCFILE_DIRS tag can be used to specify one or more directories that
+# contain msc files that are included in the documentation (see the \mscfile
+# command).
+
+MSCFILE_DIRS           =
+
+# The DIAFILE_DIRS tag can be used to specify one or more directories that
+# contain dia files that are included in the documentation (see the \diafile
+# command).
+
+DIAFILE_DIRS           =
+
+# When using plantuml, the PLANTUML_JAR_PATH tag should be used to specify the
+# path where java can find the plantuml.jar file or to the filename of jar file
+# to be used. If left blank, it is assumed PlantUML is not used or called during
+# a preprocessing step. Doxygen will generate a warning when it encounters a
+# \startuml command in this case and will not generate output for the diagram.
+
+PLANTUML_JAR_PATH      =
+
+# When using plantuml, the PLANTUML_CFG_FILE tag can be used to specify a
+# configuration file for plantuml.
+
+PLANTUML_CFG_FILE      =
+
+# When using plantuml, the specified paths are searched for files specified by
+# the !include statement in a plantuml block.
+
+PLANTUML_INCLUDE_PATH  =
+
+# The DOT_GRAPH_MAX_NODES tag can be used to set the maximum number of nodes
+# that will be shown in the graph. If the number of nodes in a graph becomes
+# larger than this value, doxygen will truncate the graph, which is visualized
+# by representing a node as a red box. Note that doxygen if the number of direct
+# children of the root node in a graph is already larger than
+# DOT_GRAPH_MAX_NODES then the graph will not be shown at all. Also note that
+# the size of a graph can be further restricted by MAX_DOT_GRAPH_DEPTH.
+# Minimum value: 0, maximum value: 10000, default value: 50.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_GRAPH_MAX_NODES    = 100
+
+# The MAX_DOT_GRAPH_DEPTH tag can be used to set the maximum depth of the graphs
+# generated by dot. A depth value of 3 means that only nodes reachable from the
+# root by following a path via at most 3 edges will be shown. Nodes that lay
+# further from the root node will be omitted. Note that setting this option to 1
+# or 2 may greatly reduce the computation time needed for large code bases. Also
+# note that the size of a graph can be further restricted by
+# DOT_GRAPH_MAX_NODES. Using a depth of 0 means no depth restriction.
+# Minimum value: 0, maximum value: 1000, default value: 0.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+MAX_DOT_GRAPH_DEPTH    = 0
+
+# Set the DOT_TRANSPARENT tag to YES to generate images with a transparent
+# background. This is disabled by default, because dot on Windows does not seem
+# to support this out of the box.
+#
+# Warning: Depending on the platform used, enabling this option may lead to
+# badly anti-aliased labels on the edges of a graph (i.e. they become hard to
+# read).
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_TRANSPARENT        = YES
+
+# Set the DOT_MULTI_TARGETS tag to YES to allow dot to generate multiple output
+# files in one run (i.e. multiple -o and -T options on the command line). This
+# makes dot run faster, but since only newer versions of dot (>1.8.10) support
+# this, this feature is disabled by default.
+# The default value is: NO.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+DOT_MULTI_TARGETS      = YES
+
+# If the GENERATE_LEGEND tag is set to YES doxygen will generate a legend page
+# explaining the meaning of the various boxes and arrows in the dot generated
+# graphs.
+# Note: This tag requires that UML_LOOK isn't set, i.e. the doxygen internal
+# graphical representation for inheritance and collaboration diagrams is used.
+# The default value is: YES.
+# This tag requires that the tag HAVE_DOT is set to YES.
+
+GENERATE_LEGEND        = YES
+
+# If the DOT_CLEANUP tag is set to YES, doxygen will remove the intermediate
+# files that are used to generate the various graphs.
+#
+# Note: This setting is not only used for dot files but also for msc temporary
+# files.
+# The default value is: YES.
+
+DOT_CLEANUP            = YES
diff --git a/doc/README.api b/doc/README.api
new file mode 100644
index 0000000..8d72f63
--- /dev/null
+++ b/doc/README.api
@@ -0,0 +1,35 @@
+This is an (incomplete) list of currently provided APIs by dpkg, and
+their supported status.
+
+
+What: libdpkg.a (C static library)
+Status: volatile
+Description:
+ The API provided by this library is highly volatile, still in the process
+ of being cleaned up. It's only supposed to be used internally by dpkg for
+ now. Header files, functions, variables and types might get renamed,
+ removed or change semantics. If you still have a need to use it, which
+ you'd be doing anyway, say by locally building dpkg to get the library,
+ then define the C preprocessor macro LIBDPKG_VOLATILE_API in your build
+ to acknowledge that fact.
+
+What: libdpkg-perl (perl modules)
+Status: stable
+Description:
+ Among the perl modules provided by libdpkg-perl, you can safely rely on
+ those that have $VERSION set to 1.00 (or higher). Note however that the
+ API is defined by what's documented in the corresponding manual pages and
+ nothing more. You can't assume anything else based on what you read in
+ the source code. If you feel the need for further refinements in the
+ documented API, don't hesitate to file a wishlist bug against
+ libdpkg-perl.
+ .
+ In case of API-breaking changes, the major number in $VERSION will be
+ increased. For API extensions, the minor number will be increased.
+
+What: custom changelog parsers as Dpkg::Changelog derived modules
+Status: stable
+Description:
+ Since dpkg 1.18.8, custom changelog parsers are supported as modules
+ derived from the Dpkg::Changelog module. The derived modules need to
+ implement all required documented methods.
diff --git a/doc/README.feature-removal-schedule b/doc/README.feature-removal-schedule
new file mode 100644
index 0000000..928880f
--- /dev/null
+++ b/doc/README.feature-removal-schedule
@@ -0,0 +1,174 @@
+This is a list of features that are scheduled to be removed from dpkg.
+
+What: fallback of dpkg-source to source format "1.0" without explicit debian/source/format
+Status: deprecated
+When: 1.17.x
+Warning: program and lintian (missing-debian-source-format)
+Why:
+ With the support of multiple source formats, the user should be explicit
+ about the desired source format. The fallback to "1.0" is there only for
+ backwards compatibility but will be removed once all packages have the
+ debian/source/format file. This is unlikely to happen before 1.17.x.
+
+What --forget-old-unavail (dpkg option)
+Status: obsolete
+When: 1.16.x
+Warning: program
+Why:
+ Purged packages are properly cleaned up now by dpkg, and old unavailable
+ leftovers are automatically cleaned up on database parsing. So there's no
+ need anymore for this manual action.
+
+What: --control-path (dpkg-query option)
+Status: deprecated
+When: 1.18.x
+Warning: man page
+ This was a semi-public interface now superseded by --control-list and
+ --control-show, which are a better interface as they do not rely on any
+ specific database layout. Although there might still be cases where it's
+ required to avoid hardcoding the database layout, and it will be kept as
+ long as there's legitimate uses for it and no viable replacements.
+
+What: -L (dpkg-parsechangelog option)
+Status: obsolete
+Since: 1.18.8
+When: 1.19.x
+Warning: program
+Why:
+ The custom parsers have been switched from programs to perl modules,
+ and this option has no use any longer. The caller can set PERL5LIB or
+ PERLLIB to specify the perl module search path now.
+
+History of feature removals
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+What: cleanup-info (program)
+Status: removed
+Since: 1.15.0
+Why:
+ This program was needed long time ago to fixup broken info dir files
+ generated by buggy install-info programs. Should not be needed anymore.
+
+What: --largemem, --smallmem (dpkg option)
+Status: removed
+When: 1.15.1
+Why:
+ These options have been no-ops for a long time.
+
+What: --force-auto-select (dpkg option)
+Status: removed
+When: 1.15.1
+Why:
+ This option has been a no-op for so long, that there's no traces on git
+ history of its usage.
+
+What: recommended, contrib, base (priority)
+Status: removed
+When: 1.15.1
+Why:
+ These priorities have been superseded by either other fields or values in
+ other fields.
+
+What: 822-date (program)
+Status: removed
+When: 1.15.1
+Why:
+ Should switch to use 'date -R'.
+
+What: support of custom changelog parsers understanding only -v
+Status: removed
+Since: 1.15.5
+Why:
+ The debian changelog parser has been enhanced. It supports new options
+ that enable more fine-grained retrieval of information. Those new options
+ will be used by scripts (like dpkg-genchanges).
+ .
+ Custom changelog parsers must be updated to support the new API (see
+ dpkg-parsechangelog(1) and README.api).
+
+What: support for environment variable DPKG_NO_TSTP
+Status: removed
+Since: 1.15.6
+Why:
+ Having two ways to let the administrator get to a shell on conffile prompt
+ is confusing, it also impedes setting up a consistent environment to be
+ used by external programs.
+
+What: support for PGP
+Status: removed
+When: 1.16.4
+Warning: program
+Why:
+ PGP is not part of Debian and GnuPG has been the standard tool for digital
+ signatures for several years already. Supporting only GnuPG enables us to
+ rely on some of its features.
+
+What: -u, --udeb (dpkg-scanpackages option)
+Status: removed
+When: 1.16.4
+Warning: program
+Why:
+ This option has been superseded by -tudeb.
+
+What: support for custom changelog parsers as programs
+Status: removed
+Since: 1.18.8
+Why:
+ Using programs to implement the custom changelog parsers was very inefficient
+ as it required to parse the custom changelog, output deb822 formatted entries
+ to then parse that and output again with the desired format.
+ .
+ These were implemented as programs because at the time the perl code in dpkg
+ was not using perl modules, so it was not easy to extend. Using perl modules
+ now is cleaner and allows for a faster implementation.
+ .
+ In addition there's no known users in Debian, so it was deemed safe to remove
+ the support without a transition.
+
+What: Source-Version (substvar)
+Status: removed
+When: 1.18.11
+Warning: program, lintian (substvar-source-version-is-deprecated)
+Why:
+ The semantics of Source-Version were misleading when applied to binNMUs.
+ Should switch to use binary:Version or source:Version substvars.
+ .
+ The code got changed to emit errors.
+
+What: -Zlzma (dpkg-deb option value)
+Status: removed
+When: 1.18.11
+Warning: program
+Why:
+ LZMA compression has some format deficiencies fixed by XZ, which is what
+ upstream has replaced it with, as such there's no point in continuing to
+ support compressing new .deb files with that format, although unpacking
+ will be kept being supported to handle existing compressed files.
+
+What: -Zbzip2 (dpkg-deb option value)
+Status: removed
+When: 1.18.11
+Warning: program
+Why:
+ bzip2 compression has been superseded by xz when it comes to size, and
+ gzip is still faster, in Debian there's really not many packages using
+ that compression, as such there's no point in continuing to support
+ compressing new .deb files with that format, although unpacking
+ will be kept being supported to handle existing compressed files.
+
+What: --new, --old (dpkg-deb options)
+Status: removed
+When: 1.18.11
+Warning: program
+Why:
+ These options are not future-proof, and do not give the caller any
+ guarantee of what exact format version will be used to produce the
+ output file. They were replaced with a new --deb-format option.
+
+What: --print-installation-architecture (dpkg option)
+Status: removed
+When: 1.18.11
+Warning: program
+Why:
+ Obsoleted long time ago (2005-01-22). Remaining packages should switch to
+ use 'dpkg --print-architecture'.
diff --git a/doc/coding-style.txt b/doc/coding-style.txt
new file mode 100644
index 0000000..af04592
--- /dev/null
+++ b/doc/coding-style.txt
@@ -0,0 +1,343 @@
+Dpkg POD coding style 2021-06-25
+=====================
+
+General
+~~~~~~~
+
+Verbatim code sections that need to be formatted, need to be prefixed with
+a line containing exactly «Z<>», to trick the parser.
+
+New sentences inside a paragraph should start on a new line, so that we
+do not need to reflow the text when adding new content.
+
+Every new feature, option or behavior change needs to be documented with
+the version introducing the change.
+
+
+Dpkg M4sh/Autoconf coding style 2016-09-05
+===============================
+
+General
+~~~~~~~
+
+All dpkg specific macros need to be prefixed with «DPKG_». Complex checks
+should be defined as new macros under m4/dpkg-<name>.m4, and those used
+in configure.ac which should look pretty simple.
+
+Quoting and indentation
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Code and arguments that wrap into the next line are indented by two spaces.
+
+In principle all macro argument should always be quoted. Which brings one
+of the biggest readability issues with M4sh/Autoconf code, the amount of
+consecutive quotes and parenthesis pairs, which can make it very hard to
+notice if they are unbalanced. To avoid this we use a style that tries to
+avoid more than two consecutive blocks of «])».
+
+We can either use a style resembling very simple function calls, when the
+arguments are as well very simple, such as:
+
+  AC_DEFINE_UNQUOTED([SOME_VARIABLE],
+    [SOME_CONCOCTED_WAY_TO_GET_A_VALUE],
+    [Some descriptive text here])
+
+  AS_CASE([condition],
+    [case-a], [do-a],
+    [case-b], [do-b])
+
+Or one resembling curly-braced C-style blocks, such as this:
+
+  AS_IF([condition], [
+    DO_SOMETHING([here])
+  ], [
+    DO_OTHERWISE([there])
+  ])
+
+Except for AC_ARG_WITH, AC_ARG_ENABLE and AM_CONDITIONAL which need their
+second argument quoted tightly surrounding the code, like this:
+
+  AC_ARG_ENABLE([feature],
+    [AS_HELP_STRING([--disable-feature], [Disable feature])],
+    [], [enable_feature="yes"])
+
+  AM_CONDITIONAL([HAVE_SOME_FEATURE],
+    [test "x$ac_cv_have_some_feature" = "xyes" && \
+     test "x$ac_cv_have_some_feature" = "xyes"])
+
+or the output will get messed up.
+
+
+Dpkg C/C++ coding style 2016-01-29
+=======================
+
+C language extensions
+~~~~~~~~~~~~~~~~~~~~~
+
+The code base assumes C89 plus the following C99 extensions:
+
+ * Designated initializers.
+ * Compound literals.
+ * Trailing comma in enum.
+ * Variadic macros.
+ * Working bool type in <stdbool.h>.
+ * Working %j and %z printf modifiers.
+ * Magic __func__ variable.
+
+Those are checked at build time, and it will abort in case a needed extension
+is not supported.
+
+C++ language extensions
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The code base assumes C++03 plus the following C++11 extension:
+
+ * Null pointer keyword (nullptr).
+
+This is checked at build time, and it will use compatibility code in case the
+needed extension is not supported.
+
+General
+~~~~~~~
+
+The coding style is a mix of parts from KNF [K] and the Linux CodingStyle [L].
+If in doubt or missing from this file please ask, although files using the
+tab based indentation can be considered canon.
+
+  [K] <https://www.freebsd.org/cgi/man.cgi?query=style>
+  [L] <https://www.kernel.org/doc/Documentation/CodingStyle>
+
+The code has a mix of an old coding style being phased out and the new
+style. New files should use the new style, changes to files with the old
+style should switch the code being touched except for the indentation level,
+which should be preserved to match (2 spaces).
+
+Code should generally strive for clarity. Monster functions should be split
+into logical and small pieces.
+
+Variable and function names should be generally descriptive, not needed
+for variables commonly used (for example an index inside a loop, etc),
+acronyms should only be used if they are widely known externally or
+inside the project. The names should separate logical concepts within
+with underscores.
+
+On comments use UTF-8 characters for quotes, copyright symbols, etc.
+
+On strings in code use simple or double quotes «''» «""». Not the unpaired
+ones «`'». Strings marked for translation, should only be fixed if there's
+other changes to be done on them, otherwise we get unneeded fuzzies.
+
+  <https://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html>
+
+Code documentation
+~~~~~~~~~~~~~~~~~~
+
+Public declarations should be documented using JavaDoc style comments.
+
+Documentation should always be close to its definition (usually in the .c
+or .cc files) and not its declaration, so that when the code changes it's
+less likely that they will get out of sync. For data types, macros and
+similar where there's only declarations, the documentation will usually
+go instead in the header files.
+
+For enum values and struct members, the documentation should usually be
+one-line comments, preceding the item.
+
+The comment title should be on the second line on its own, and the long
+description on its own paragraph.
+
+Examples:
+
+/**
+ * This is the enum title.
+ */
+enum value_list {
+	/** Value doing foo. */
+	VALUE_A,
+	/** Value doing bar. */
+	VALUE_B,
+};
+
+/**
+ * This is the title.
+ *
+ * This is the long description extending several lines, explaining in
+ * detail what this item does.
+ *
+ * @param a This is the a parameter.
+ * @param b This is the b parameter.
+ *
+ * @return This is the return value.
+ */
+
+Indentation, alignment and spacing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Lines should be 80 chars max. Indentation is done with hard tabs (which
+should be considered to take 8 spaces width). Aligning with spaces:
+
+static void
+function(void *ptr, int value)
+{
+	void *ref_ptr = get_ref(ptr);
+	int ref_value = get_value(ref);
+
+	if (value > 10)
+		do_something(GLOBAL_MACRO, ptr, value, "some-string",
+		             ref_ptr, ref_value, "other-string",
+		             "extra-string");
+}
+
+When wrapping, logical operators should be kept on the preceding line:
+
+	if (really_long_variable_to_be_checked_against_a &&
+	    really_long_variable_to_be_checked_against_b)
+		foo();
+
+Spaces around operators:
+
+	if (a && (b || c) && c == d)
+		break;
+
+	a = (b + 4 * (5 - 6)) & 0xff;
+
+Spaces around assignments:
+
+	a += b;
+
+Spaces after comma:
+
+	foo(a, b);
+
+Space after keywords (for, while, do, if, etc, but sizeof should be
+treated like a function):
+
+	for (i = 0; i < 10; i++)
+		foo(i);
+
+	memcpy(dst, src, sizeof(src));
+
+Definition of local variables, related code blocks, functions bodies
+should be split with blank lines:
+
+int
+function(void)
+{
+	int a;
+
+	foo();
+	bar();
+
+	quux();
+
+	return 0;
+}
+
+Braces
+~~~~~~
+
+Braces should be placed on the same line as the keyword, but on a new line
+for the function body. No braces should be used for unambiguous one line
+statements:
+
+	if (a > 0) {
+		foo(a);
+		bar(a);
+	} else {
+		quux(0)
+		bar(0);
+	}
+
+	for (;;) {
+		foo();
+		bar();
+	}
+
+	do {
+		foo();
+		bar();
+	} while (quux());
+
+	switch (foo) {
+	case a:
+		bar();
+		break;
+	case b:
+	default:
+		baz();
+		break;
+	}
+
+Code conventions
+~~~~~~~~~~~~~~~~
+
+Prefer assigning outside of conditionals:
+
+	n = read_items();
+	if (n < 100)
+		foo();
+
+String comparisons should use comparison operators to make it easier to
+see what operation is being done:
+
+	if (strcmp(a, b) == 0)
+		foo();
+
+	if (strcmp(a, b) < 0)
+		foo();
+
+
+Dpkg Perl coding style 2019-03-27
+======================
+
+General
+~~~~~~~
+
+In general you should follow the conventions listed in perlstyle(1).
+All the code should run with the “use strict” and “use warnings” pragmas,
+and pass «make authorcheck».
+
+Code documentation
+~~~~~~~~~~~~~~~~~~
+
+Public modules should be documented with POD (see perlpod(1)). Private
+code doesn't have to use POD, simple comment lines (starting with "#") are
+enough, but if they use POD they need to note the fact that the module is
+private in the CHANGES section and specify a version «0.xx». Public scripts
+are documented in their corresponding manual pages.
+
+Indentation, alignment and spacing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Lines should be 80 chars max. The indentation level is 4 characters, and
+indentation is done with soft tabs (no hard tabs) and spaces.
+
+if ($foo) {
+    if ($bar) {
+        print "Hello\n";
+        unless ($baz) {
+            print "Who are you?\n";
+        }
+    }
+}
+
+Perl version
+~~~~~~~~~~~~
+
+We don't want to impose a too-recent Perl version, so only use features
+supported by the Perl version that is currently in Debian oldstable when
+possible. Currently that means Perl 5.28.1.
+
+Object methods
+~~~~~~~~~~~~~~
+
+Use a single line to retrieve all the arguments and use $self as name
+for the current object:
+
+sub do_something {
+    my ($self, $arg1, $arg2, %opts) = @_;
+    ...
+}
+
+Supplementary optional arguments should be named and thus stored in a
+hash.
diff --git a/doc/spec/frontend-api.txt b/doc/spec/frontend-api.txt
new file mode 100644
index 0000000..9ea1e20
--- /dev/null
+++ b/doc/spec/frontend-api.txt
@@ -0,0 +1,24 @@
+Frontend Interfaces
+===================
+
+This file will try to document some of the interfaces that dpkg makes
+available to frontends or that expects them to use, which are currently
+not covered by any other type of documentation.
+
+
+Database Locking
+----------------
+
+Any frontend needing to make sure no write operation is currently happening,
+and no other frontend is running should first acquire the frontend lock at
+«<admindir>/lock-frontend», and then acquire the dpkg database lock at
+«<admindir>/lock». When the frontend invokes dpkg, it should set the
+environment variable DPKG_FRONTEND_LOCKED (to prevent dpkg from acquiring
+the frontend lock), and then release the dpkg database lock, which will be
+acquired by dpkg itself. This way no other frontend following this protocol
+can race to perform operations while another one has one in progress.
+
+These locks must be file record locks (i.e. fcntl(2) advisory locking), and
+the whole file should be locked, as that's the most portable way to perform
+this operation; this can be achieved by using start=0, len=0 and
+whence=SEEK_SET.
diff --git a/doc/spec/protected-field.txt b/doc/spec/protected-field.txt
new file mode 100644
index 0000000..90e2441
--- /dev/null
+++ b/doc/spec/protected-field.txt
@@ -0,0 +1,74 @@
+Support for a Protected field
+=============================
+
+Status: draft, experimental
+URL: https://wiki.debian.org/Teams/Dpkg/Spec/ProtectedField
+
+Summary
+-------
+
+The goal of the following proposal is to standardize a field to split
+part of the «Essential» packages, and add support for it in the package
+management stack. There is currently an Important field, that has the
+correct semantics but has a very confusing name and is only supported
+by apt anyway, so this new field would phase out that one.
+
+Background
+----------
+
+Our current use of «Essential: yes» is confused, and it includes several
+conflated things, some of which would be worth splitting up.
+
+We use «Essential» to:
+
+  * Denote that a package must be always installed and cannot be
+    removed (easily), because it is essential to the system in some way.
+  * Denote that a package must be functional even when just unpacked
+    (after having been configured once / fully bootstrapped).
+  * Mark auto-vivification, by making front-ends either complain very
+    loudly or reinstalling these packages when missing.
+  * Minimize dependency loops, by making these dependencies implicit.
+
+One problem is that the first point above includes being essential for
+the packaging system during upgrades/installation, for the operation
+of the system in general, and for the operation of the system during
+boot.
+
+The latter is not always necessary though, for example within a chroot,
+or some types of containers. There has been work on trying to trim down
+the pseudo-essential set as can be seen from:
+
+  <https://wiki.debian.org/Proposals/EssentialOnDiet>
+  <https://wiki.debian.org/BusterPriorityRequalification>
+
+And several of these switches made use of a pre-existing field called
+«Important», defined and currently only supported by apt, which had the
+following properties:
+
+  * These packages are not required to be installed.
+  * They do not have to be usable while unconfigured.
+  * Dependencies need to be spelled out.
+
+Proposal
+--------
+
+The proposal would be to add support for a new Protected field, with the
+following properties:
+
+  * Protected packages should not be trivial to remove (require a force
+    option for example, like «Essential»).
+  * Protected packages should not be required to be installed (i.e. once
+    removed they should not be automatically brought back by a front-end,
+    unlike «Essential»).
+  * Protected packages must be depended on explicitly (unlike «Essential»).
+  * Protected packages must be functional even when unpacked (think of
+    a boot loader or an init system; like «Essential»). [XXX: This one is
+    not entirely clear and might not match reality anyway, for example kernels,
+    which might require building an initramfs, etc.]
+
+This would make it possible to phase out the current «Important» field
+usage (because it has a name too confusing relative to the «Priority»
+value; and has small tooling coverage) and the usage of «Essential» for
+at least packages involved in the boot process, and perhaps also for
+packages essential for operation of the system in general (in contrast
+to packages required for the packaging system).
diff --git a/doc/spec/rootless-builds.txt b/doc/spec/rootless-builds.txt
new file mode 100644
index 0000000..af0a328
--- /dev/null
+++ b/doc/spec/rootless-builds.txt
@@ -0,0 +1,177 @@
+Supporting rootless builds
+==========================
+
+Status: recommendation, stable
+Version: 1.0
+
+Background
+----------
+
+Traditionally, Debian packages have required (fake)root privileges for some
+of the "debian/rules" targets. This has required also a split between build
+and binary targets; making the builds slower, due to the increased amount
+of invocations of "debian/rules" and the overhead of using fakeroot(1) or
+equivalent fake environments, or less secure due to the increased dangers
+of running under real root via sudo or equivalent.
+
+On this document when talking about "(fake)root" privileges, it will refer
+to any mechanism, supported by the dpkg-buildpackage "-r/--root-command"
+option, that can provide either a real or faked root user environment.
+
+Specification
+-------------
+
+We add a new field to the "Source" stanza of debian/control:
+
+  Rules-Requires-Root: no | binary-targets | <implementations-keywords>
+
+The case sensitive values are defined as:
+
+ * If "no", then "debian/rules binary" will not require root at all (not even
+   fakeroot).
+   - If the "no" keyword is used, it MUST be the only keyword in that field
+     and MUST appear exactly once.
+
+ * If "binary-targets", then "debian/rules binary" (etc.) must always be run
+   under (fake)root. This is the default/status quo.
+
+ * <implementations-keywords> will be a space separated list of keywords which
+   define when root is required.
+
+   - Keywords consists of <namespace>/<cases>. The "namespace" part cannot
+     contain "/" or whitespace. The "cases" part cannot contain whitespace.
+     Furthermore, both parts MUST consist entirely of printable ASCII
+     characters.
+
+   - Each tool/package will define a namespace named after itself and provide
+     a number of cases where (fake)root is required.
+     (See also "Implementation provided keywords".)
+
+   - When "Rules-Requires-Root" is set to <implementations-keywords>, the
+     builder (i.e. whatever is executing debian/rules) will expose an
+     interface that is used to run a command under (fake)root via the
+     "Gain Root API". If the builder cannot provide such a command, it
+     MUST behave like "Rules-Requires-Root" was set to "binary-targets",
+     i.e. run "debian/rules binary" under (fake)root.
+
+When the builder supports this specification, it MUST notify this fact to
+the rules file via the "DEB_RULES_REQUIRES_ROOT" environment variable, with
+the value it has obtained from the Rules-Requires-Root field or some builder
+specific override mechanism, which will denote the level of support the
+builder has chosen to commit to take effect during the build. When set,
+it MUST be a valid value for the Rules-Requires-Root field. If unset,
+the build system SHOULD assume that the builder does not recognize the
+Rules-Requires-Root field at all.
+
+It is always permissible for a builder to ignore this field and fall back to
+running the binary targets under (fake)root. This is to ensure backwards
+compatibility when builds are performed by legacy builders or older versions
+of the tooling.
+
+Tools called from the rules file MUST cope gracefully with being called under
+(fake)root even when Rules-Requires-Root is set to a value that implies they
+should not be (e.g. "no"). However, they MUST NOT attempt to run processes
+under (fake)root when run as a regular user when Rules-Requires-Root does
+not list any keywords they respond to.
+
+Tools MUST gracefully ignore valid unknown keywords outside their namespace.
+They MAY warn about unknown keywords inside their namespace.
+
+The value of this field MUST NOT change the content of the package in any
+way. Notably, packages that are bit-for-bit reproducible MUST still provide
+bit-for-bit identical results even when the field is ignored.
+
+Implementation provided keywords
+--------------------------------
+
+Keywords provided by various implementations:
+
+ * dpkg/target-subcommand: When the package needs to run a given command
+   under (fake)root within the "debian/rules" files directly, this MUST be
+   declared via this keyword.
+
+ * dpkg/target/<target-name>: When a specific "debian/rules" unofficial
+   target (none of the root-requiring "binary-indep", "binary-arch", "binary",
+   "clean", nor the non-root-requiring "build-indep", "build-arch", "build")
+   needs to be run under (fake)root, this MUST be declared via this dynamic
+   keyword, where <target-name> is the name of the "debian/rules" target.
+
+ * debhelper/upstream-make-install: The dh_auto_install command will run
+   the "install" target from the upstream's Makefile under (fake)root (for
+   the "makefile" build system or one derived from it).
+
+Gain Root API
+-------------
+
+The builder will provide a command to promote a given command to (fake)root
+by exposing it in the environment variable "DEB_GAIN_ROOT_CMD". Tools that
+need this promotion will then use it like the following:
+
+    $DEB_GAIN_ROOT_CMD cmd-that-needs-root ...
+
+This command is subject to the same requirements as the "gain-root-command"
+that dpkg-buildpackage accepts via its "-r/--root-command" option, which
+means that it can contain space-separated parameters. If dpkg-buildpackage is
+called with "-r/--root-command", then dpkg-buildpackage shall use that value
+as the value for "DEB_GAIN_ROOT_CMD". The command SHOULD preserve all the
+environment variables, unmodified.
+
+The variable SHOULD only be provided when there is a need for it. Notably
+when "Rules-Requires-Root" is either "no" or "binary-targets" the variable
+SHOULD NOT be defined.
+
+(The "DEB_GAIN_ROOT_CMD" variable used to be named "DPKG_GAIN_ROOT_CMD"
+starting with dpkg 1.19.0 and before dpkg 1.19.1 when this specification
+got released as stable. The old name MUST not be used.)
+
+Common cases
+------------
+
+ * Upstream installation insists on "sudo make install"-like behaviour.
+   => Use dpkg/target-subcommand or debhelper/upstream-make-install.
+
+ * Files shipped in the package must be owned by another user than root.
+   => Not covered; use "binary-targets" for now until dpkg+debhelper
+      provides the required interface.
+
+Prototyping/preparation
+=======================
+
+dpkg side
+---------
+
+dpkg-deb --build provides the --root-owner-group option so that dh_builddeb
+or direct calls can control the owner/group file values w/o requiring
+(fake)root.
+
+dpkg-buildpackage must export DEB_GAIN_ROOT_CMD when necessary (for
+prototyping, doing this unconditionally would be fine).
+
+
+debhelper side
+--------------
+
+When the field is present:
+
+ * dh_testroot will behave as usual when Rules-Requires-Root is not present
+   or set to "binary-targets".
+
+ * dh_testroot will be a no-op when Rules-Requires-Root is set to "no".
+
+ * Otherwise, dh_testroot will either verify that it is run under (fake)root
+   (as usual) OR assert that DEB_GAIN_ROOT_CMD is defined.
+
+ * debhelper build systems will be patched to check for the
+   "debhelper/upstream-make-install" keyword and use the "Gain Root API"
+   accordingly.
+
+ * All other (src:)debhelper commands will skip their calls to chown
+   (currently they just reset them to "0:0" anyway).
+
+With the above, a default "dh $@" will no longer require (fake)root when
+built (and Rules-Requires-Root is "no").
+
+Prototyping:
+
+ * During prototyping, dh_builddeb can wrap the dpkg-deb --build call with
+   fakeroot (when not already root).
diff --git a/doc/spec/triggers.txt b/doc/spec/triggers.txt
new file mode 100644
index 0000000..a8de984
--- /dev/null
+++ b/doc/spec/triggers.txt
@@ -0,0 +1,816 @@
+TRIGGERS
+========
+
+Introduction
+------------
+
+A dpkg trigger is a facility that allows events caused by one package
+but of interest to another package to be recorded and aggregated, and
+processed later by the interested package.  This feature simplifies
+various registration and system-update tasks and reduces duplication
+of processing.
+
+(NB: Triggers are intended for events that occur during package
+installation, not events that occur in general operation.)
+
+
+Concepts
+--------
+
+Each trigger is named, and at any time zero or more packages may be
+interested in it.
+
+We currently envisage three kinds of triggers:
+ * Explicit triggers.  These can be activated by any program
+   by running dpkg-trigger (at any time, but ideally from a maintainer
+   script).
+ * File triggers.  These are activated automatically by dpkg
+   when a matching file is installed, upgraded or removed as part
+   of a package.  They may also be explicitly activated by running
+   dpkg-trigger.
+ * Future kinds of special triggers, which are activated by magic code
+   in dpkg itself.  Currently none are defined besides file triggers.
+
+A trigger is always activated by a particular package.
+
+Trigger names contain only printing 7-bit ascii characters (no
+whitespace).  Each trigger kind has a distinct subset of the trigger
+name space so that the kind can be determined from the name.  After we
+run out of straightforward syntaxes, we will use <kind>:<details>.
+
+When a trigger is activated, it becomes pending for every package
+which is interested in the trigger at that time.  Each package has a
+list of zero or more pending triggers.  Repeated activation of the
+same trigger has no additional effect.  Note that in general a trigger
+will not be processed immediately when it is activated; processing is
+deferred until it is convenient (as described below).
+
+At a trigger activation, the interested packages(s) are added to the
+triggering package's list of triggers-awaited packages (unless the
+trigger has been configured to not require it); the triggering
+package is said to await the trigger processing.
+
+A package which has pending triggers, or which awaits triggers, is not
+considered properly installed.  There are two new dpkg status values,
+‘triggers-pending’ and ‘triggers-awaited’, which lie between
+‘config-failed’ and ‘installed’.
+
+
+Details - Overview table
+------------------------
+
+  Status      Pending   Awaited   Satisfies  Remedy
+              triggers  triggers  Depends
+
+  unpacked    never      maybe    No    postinst configure
+  c.-failed   never      maybe    No    postinst configure (when requested)
+  t.-awaited  yes        always   No    postinst triggered + fix awaited pkg(s)
+  t.-awaited  no         always   No    fix awaited package(s)
+  t.-pending  always     never    Yes   postinst triggered
+  installed   never      never    Yes   n/a
+
+Packages in t-awaited and t-pending demand satisfaction of their
+dependencies just like packages in installed.
+
+
+Details - triggering package
+----------------------------
+
+When a package <T> activates a trigger in which a package <I> is
+interested, <I> is added to the list of packages whose trigger
+processing is awaited by <T>. Zero or more packages <I> may be added as a
+result of any particular trigger activation, depending on how many
+packages were interested. (If <T> chooses, explicit trigger activation
+using dpkg-trigger of <I> by <T> need not make <T> become triggers-awaited
+in this way.)
+
+A package which awaits trigger processing but would otherwise be
+‘installed’ or ‘triggers-pending’ is considered to be in state
+‘triggers-awaited’.  Packages in ‘triggers-awaited’ do not satisfy
+Depends dependencies.
+
+Every triggered package <I> in <T>'s list of awaited packages either has a
+nonempty list of pending triggers, or is in ‘config-failed’ or worse.
+When <I> enters ‘installed’ (or ‘config-files’ or ‘not-installed’), the
+entry in <T>'s list of awaited packages is removed so that <T> may, if it
+no longer awaits any packages, become ‘installed’ or ‘triggers-pending’.
+
+Packages in ‘config-files’ or ‘not-installed’ do not await triggers.
+
+
+Details - triggered package
+---------------------------
+
+When one of the triggers in which a package is interested is
+activated, the triggered package has the trigger added to its list of
+pending triggers.  Packages with a nonempty list of pending triggers
+which would otherwise be in state ‘installed’ are in state
+‘triggers-pending’ instead, so if the package was previously
+‘installed’ it becomes ‘triggers-pending’.
+
+If a package has nonempty lists both of pending and awaited triggers,
+then it is in ‘triggers-awaited’.  Nevertheless efforts will still be
+made to process its triggers so as to make the list of pending
+triggers empty.
+
+To restore a package in state ‘triggers-pending’ to ‘installed’, or to
+process pending triggers of a package with both pending and awaited
+triggers, dpkg will run the postinst script as:
+
+   postinst triggered "<trigger-name> <trigger-name> ..."
+
+by passing a space-separated list of <trigger-name>s as the second argument.
+
+This will be attempted for each relevant package at the end of each
+dpkg run; so, normally, in the same dpkg run as the event which made
+the package go to ‘triggers-pending’.  This leaves packages in
+reasonable states by default.
+
+If the “postinst triggered” run fails the package goes to
+‘config-failed’, so that the trigger processing will not be attempted
+again until explicitly requested.
+
+
+             │
+             v
+       ┌────────────┐
+       │  unpacked  │
+       └─────┬──────┘
+             │
+             │
+  (automatic)│      ┌───────────────┐
+             │      │ config-failed │
+             │      └─────┬─────────┘
+             │            │   ^
+             │            │   │
+             ├──────<─────┘   │     ┌──────────────────────────────────┐
+             │ (user request) │     │         triggers-pending         │
+  postinst   │                │     │                or                │
+ "configure" │                │     │ triggers-awaited w/ some pending │
+             │                │     └────────────┬─────────────────────┘
+             │                │                  │    ^
+             ├────────>───────┤       postinst   │    │
+             │      error     │      "triggered" │    │
+             │                │      (automatic) │    │
+             │                │                  │    │ trigger(s)
+             │                │                  │    │ activated
+             │                └────────<─────────┤    │
+             │                       error       │    │
+             │                                   │    │
+             v                                   v    │
+       ┌──────────────────────────────────────────────┴────┐
+       │   installed or triggers-awaited w/ none pending   │
+       └───────────────────────────────────────────────────┘
+
+Packages in ‘config-failed’ or worse are never considered to have
+lists of pending triggers.  A package whose postinst is being run
+can however acquire pending triggers during that run (ie, a package
+can trigger itself).
+
+This means that if a triggering package <T> awaits trigger processing by
+an interested package <I>, and <I> goes to ‘config-failed’ or worse (eg,
+during unpack for upgrade), then when <I> is reconfigured (goes to
+‘installed’) or removed, <T> will no longer await processing by <I>, so
+that <T> may automatically go from ‘triggers-awaited’ to ‘installed’.
+
+Or to put it another way, triggered actions are considered irrelevant
+if the interested package <I> is not configured. When <I>'s postinst is
+called with ‘configure’, it must do whatever actions are necessary to
+deal with any trigger activations which might have occurred while it
+was not configured, just as if the package was being configured for
+the first time.
+
+Trigger processing should be idempotent.  The list of triggers being
+processed is provided to the postinst only so that it can optimize
+away redundant processing.
+
+In that case, where an interested package has more than one trigger
+and wants to process them differently, the list of triggers can be can
+be examined in a shell script like this:
+   case " $2 " in
+   *" trigger-name-a "*)  process-trigger-a ;;
+   esac
+Generally each trigger name should be tested for separately, as the
+postinst will often be called for several triggers at once.
+
+Note that if a package both activates triggers in other packages, and
+is interested in triggers of its own, its postinst may run for trigger
+processing before the postinst(s) of the package(s) it has triggered.
+
+
+Timing guarantees, races, etc.
+------------------------------
+
+Activating a trigger will not have any immediate effect, although
+putative resulting status changes will show up in dpkg --status etc.
+(Putative because the actual status changes may depend on the state of
+trigger interests when dpkg processes the trigger activation into
+the status database, rather than that when dpkg --status is run.)
+
+A package is only guaranteed to become notified of a trigger
+activation if it is continuously interested in the trigger, and never
+in ‘config-failed’ or worse, during the period from when the trigger
+is activated until dpkg runs the package postinst (either due to
+--configure --pending, or at the end of the relevant run, as described
+above).  Subsequent to activation and before notification, the
+interested package will not be considered in state ‘installed’, so
+long as the package remains interested, and the triggering package
+will not be considered ‘installed’.
+
+If the package is not in state ‘installed’, ‘triggers-pending’ or
+‘triggers-awaited’ then pending triggers are not accumulated.
+However, if such a package (between ‘half-installed’ and
+‘config-failed’ inclusive) declares some trigger interests then the
+triggering packages *will* await their configuration (which implies
+completion of any necessary trigger processing) or removal.
+
+It is not defined in what order triggers will run.  dpkg will make
+some effort to minimize redundant work in the case where many packages
+have postinst trigger processing activating another package's triggers
+(for example, by processing triggers in fifo order during a single
+dpkg run).  Cycles in the triggering graph are prohibited and will
+eventually, perhaps after some looping, be detected by dpkg and cause
+trigger processing to fail; when this happens one of the packages
+involved will be put in state ‘config-failed’ so that the trigger loop
+will not be reattempted.  See “Cycle detection” below.
+
+
+Explicit triggers
+-----------------
+
+Explicit triggers have names with the same syntax as package names,
+*but* should *not* normally be named identically to a package.
+
+When choosing an explicit trigger name it is usually good to include a
+relevant package name or some other useful identifier to help make the
+trigger name unique.  On the other hand, explicit triggers should
+generally not be renamed just because the interested or triggering
+packages' names change.
+
+Explicit trigger names form part of the interface between packages.
+Therefore in case of wider use of any trigger the name and purpose
+should be discussed in the usual way and documented in the appropriate
+packaging guidelines (eg, in the distribution policy).
+
+
+File triggers
+-------------
+
+File triggers have names of the form
+  /path/to/directory/or/file
+and are activated when the specified filesystem object, or any object
+under the specified subdirectory, is created, updated or deleted by
+dpkg during package unpack or removal.  The pathname must be absolute.
+
+File triggers should not generally be used without mutual consent.
+The use of a file trigger, and the name of the trigger used, should be
+stated in the distribution policy, so that a package which creates a
+relevant file in a maintainer script can activate the trigger explicitly.
+
+File triggers must definitely not be used as an escalation tool in
+disagreements between different packages as to the desired contents of
+the filesystem.  Trigger activation due to a particular file should
+not generally modify that file again.
+
+Configuration files (whether dpkg-handled conffiles or not), or any
+other files which are modified at times other than package management,
+should not rely on file triggers detecting all modifications; dpkg
+triggers are not a general mechanism for filesystem monitoring.
+
+If there are or might be directory symlinks which result in packages
+referring to files by different names, then to be sure of activation
+all of the paths which might be included in packages should be listed.
+The path specified by the interested package is matched against the
+path included in the triggering package, not against the truename of
+the file as installed.  Only textually identical filenames (or
+filenames where the interest is a directory prefix of the installed
+file) are guaranteed to match.
+
+A file trigger is guaranteed to be activated before the file in
+question is modified by dpkg; on the other hand, a file trigger might
+be activated even though no file was actually modified.  Changes made
+by dpkg to the link count of a file, or to solely the inode number
+(ie, if dpkg atomically replaces it with another identical file), are
+not guaranteed to cause trigger activation.
+
+Because of the restriction on trigger names, it is not possible to
+declare a file trigger for a directory whose name contains whitespace,
+i18n characters, etc.  Such a trigger should not be necessary.
+
+
+Package declarations regarding triggers
+---------------------------------------
+
+See deb-triggers(5).
+
+Support future extension of the trigger name syntax with additional
+dpkg-generated triggers is as follows: a package which is interested
+in any unsupported trigger kinds cannot be configured (since such a
+package cannot be guaranteed to have these triggers properly activated
+by dpkg).  Therefore no package can be interested in any unsupported
+trigger kinds and they can be freely activated (both by ‘activate’ and
+by dpkg-trigger).  dpkg-deb will be changed to warn about unrecognized
+trigger names syntaxes and unrecognized trigger control directives.
+
+
+New command line interfaces to dpkg tools
+-----------------------------------------
+
+See dpkg(1).
+
+Here is a summary of the behaviours:
+
+ Command line		Trigproc	Trigproc	Configure
+			these		any triggered
+ ----------------------+---------------+---------------+-----------------
+ --unpack		no		usually[1]	none
+ --remove		n/a		usually[1]	none
+ --install		n/a		usually[1]	these
+ --configure -a		any needed	usually[1]	any needed
+ --configure <some>	if needed	usually[1]	must, or trigproc
+ --triggers-only -a	any needed	usually[1]	none
+ --triggers-only <some>	must		usually not[1]	none
+
+ [1] can be specified explicitly by --triggers or --no-triggers
+
+
+See dpkg-trigger(1).
+
+A trigger may be activated explicitly with:
+   dpkg-trigger [--by-package <package>] <name-of-trigger>
+   dpkg-trigger --no-await <name-of-trigger>
+
+There will be no output to stdout, and none to stderr unless
+dpkg-trigger is unable to make a record of the trigger activation.
+
+NB that in the case of a file trigger the name of the trigger is
+needed, not the name of a file which would match the trigger.
+
+
+apt and aptitude
+----------------
+
+These must be taught about the new ‘triggers-awaited’ and
+‘triggers-pending’ states.  Packages in these states should be treated
+roughly like those in ‘unpacked’: the remedy is to run dpkg
+--configure.
+
+Normally apt and aptitude will not see packages in ‘triggers-pending’
+since dpkg will generally attempt to run the triggers thus leaving the
+package in ‘config-failed’ or ‘installed’.
+
+Note that automatic package management tools which call dpkg (like apt
+and aptitude) should not attempt to configure individual packages in
+state ‘triggers-pending’ (or indeed ‘triggers-awaited’) with dpkg
+--triggers-only <package>... or dpkg --no-triggers --configure <package>...,
+or similar approaches. This might defeat dpkg's trigger cycle detection.
+
+A package management tool which will run dpkg --configure --pending at
+the end may use --no-triggers on its other dpkg runs.  This would be
+more efficient as it allows more aggressive deferral (and hence more
+unification) of trigger processing.
+
+
+Error handling
+--------------
+
+Packages should be written so that they DO NOT BREAK just because
+their pending triggers have not yet been run.  It is allowed for the
+functionality relating to the unprocessed trigger to fail (ie, the
+package which is awaiting the trigger processing may be broken), but
+the remainder of the interested package must work normally.
+
+For example, a package which uses file triggers to register addons
+must cope with (a) an addon being dropped into the filesystem but not
+yet registered and (b) an addon being removed but not yet
+deregistered.  In both of these cases the package's main functionality
+must continue to work normally; failure of the addon in question is
+expected, warning messages are tolerable, but complete failure of the
+whole package, or failures of other addons, are not acceptable.
+
+dpkg cannot ensure that triggers are run in a timely enough manner for
+pathological error behaviours to be tolerable.
+
+
+Where a trigger script finds bad data provided by a triggering
+package, it should generally report to stderr the problem with the bad
+data and exit nonzero, leaving the interested package in config-failed
+and the triggering package in triggers-awaited and thus signalling the
+problem to the user.
+
+Alternatively, in some situations it may be more desirable to allow
+the interested package to be configured even though it can only
+provide partial service.  In this case clear information will have to
+be given in appropriate places about the missing functionality, and a
+record should be made of the cause of the errors.  This option is
+recommended for situations where the coupling between the interested
+and triggering package is particularly loose; an example of such a
+loose coupling would be Python modules.
+
+
+
+WORKED EXAMPLE - SCROLLKEEPER
+=============================
+
+Currently, every Gnome program which comes with some help installs the
+help files in /usr/share/gnome/help and then in the postinst runs
+scrollkeeper-update.  scrollkeeper-update reads, parses and rewrites
+some large xml files in /var/lib/scrollkeeper; currently this
+occurs at every relevant package installation, upgrade or removal.
+
+When triggers are available, this will work as follows:
+
+ * gnome-foobar will ship its «omf» file in /usr/share/omf as
+   normal, but will not contain any special machinery to invoke
+   scrollkeeper.
+
+ * scrollkeeper will in its triggers control file say:
+       interest /usr/share/omf
+   and in its postinst say:
+       scrollkeeper-update-now -q
+
+   dpkg will arrange that this is run once at the end of each run
+   where any documentation was updated.
+
+   Note that it is not necessary to execute this only on particular
+   postinst "$1" values; however, at the time of writing, scrollkeeper
+   does this:
+
+       if [ "$1" = "configure" ]; then
+         printf "Rebuilding the database. This may take some time.\n"
+         scrollkeeper-rebuilddb -q
+       fi
+
+   and to retain this behaviour, something along the following lines
+   would be sensible:
+
+       if [ "$1" = "configure" ]; then
+         printf "Rebuilding the database. This may take some time.\n"
+         scrollkeeper-rebuilddb -q
+       else
+         printf "Updating GNOME help database.\n"
+         scrollkeeper-update-now -q
+       fi
+
+ * dh_scrollkeeper will only adjust the DTD declarations and no longer
+   edit maintainer scripts.
+
+
+Full implementation of the transition plan defined below, for
+scrollkeeper, goes like this:
+
+ 1. Update scrollkeeper:
+     - Add a ‘triggers’ control archive file containing
+           interest /usr/share/omf
+     - Make the postinst modifications as described above.
+     - Rename scrollkeeper-update to scrollkeeper-update-now
+     - Provide a new wrapper script as scrollkeeper-update:
+	   #!/bin/sh
+	   set -e
+	   if type dpkg-trigger >/dev/null 2>&1 && \
+	      dpkg-trigger /usr/share/omf; then
+		 exit 0
+	   fi
+	   exec scrollkeeper-update-now "$@"
+
+ 2. In gnome-policy chapter 2, “Use of scrollkeeper”,
+     - delete the requirement that the package must depend on
+       scrollkeeper
+     - delete the requirement that the package must invoke
+       scrollkeeper in the postinst and postrm
+     - instead say:
+
+         OMF files should be installed under /usr/share/omf in the
+         usual way.  A dpkg trigger is used to arrange to update the
+         scrollkeeper documentation index automatically and no special
+         care need be taken in packages which supply OMFs.
+
+         If an OMF file is placed, modified or removed other than as
+         a file installed in the ordinary way by dpkg, the dpkg file
+         trigger «/usr/share/omf» should be activated; see the dpkg
+         triggers specification for details.
+
+         Existing packages which Depend on scrollkeeper (>= 3.8)
+         because of dh_scrollkeeper or explicit calls to
+         scrollkeeper-update should be modified not to Depend on
+         scrollkeeper.
+
+ 3. Update debhelper's dh_scrollkeeper not to edit maintainer
+    scripts.  One of dh_scrollkeeper or lintian should be changed to
+    issue a warning for packages with scrollkeeper (>= 3.8) in the
+    Depends control file line.
+
+ 4. Remove the spurious dependencies on scrollkeeper, at our leisure.
+    As a bonus, after this is complete it will be possible to remove
+    scrollkeeper while keeping all of the documentation-supplying
+    gnome packages installed.
+
+ 5. If there are any packages which do by hand what dh_scrollkeeper
+    does, change them not to call scrollkeeper-update and drop
+    their dependency on scrollkeeper.
+
+This is not 100% in keeping with the full transition plan defined
+below: if a new gnome package is used with an old scrollkeeper, there
+is some possibility that the help will not properly be available.
+
+Unfortunately, dh_scrollkeeper doesn't generate the scrollkeeper
+dependency in the control file, which makes it excessively hard to get
+the dependency up to date.  The bad consequences of the inaccurate
+dependencies are less severe than the contortions which would be
+required to deal with the problem.
+
+
+TRANSITION PLAN
+===============
+
+
+Old dpkg to new dpkg
+--------------------
+
+The first time a trigger-supporting dpkg is run on any system, it will
+activate all triggers in which anyone is interested, immediately.
+
+These trigger activations will not be processed in the same dpkg run,
+to avoid unexpectedly processing triggers while attempting an
+unrelated operation.  dpkg --configure --pending (and not other dpkg
+operations) will run the triggers, and the dpkg postinst will warn the
+user about the need to run it (if this deferred triggers condition
+exists).  (Any triggers activated or reactivated *after* this
+mass-activation will be processed in the normal way.)
+
+To use this correctly:
+ * Packages which are interested in triggers, or which want to
+    explicitly activate triggers, should Depend on the
+    triggers-supporting version of dpkg.
+ * Update instructions and tools should arrange to run
+    dpkg --configure --pending
+   after the install; this will process the pending triggers.
+
+dpkg's prerm will check for attempts to downgrade while triggers are
+pending and refuse.  (Since the new dpkg would be installed but then
+refuse to read the status file.)  In case this is necessary a separate
+tool will be provided which will:
+  * Put all packages with any pending triggers into state
+    ‘config-failed’ and remove the list of pending triggers.
+  * Remove the list of awaited triggers from every package.  This
+    may cause packages to go from ‘triggers-awaited’ to ‘installed’
+    which is not 100% accurate but the best that can be done.
+  * Remove /var/lib/dpkg/triggers (to put the situation to that which
+    we would have seen if the trigger-supporting dpkg had never been
+    installed).
+
+
+Higher-level programs
+---------------------
+
+The new dpkg will declare versioned Conflicts against apt and aptitude
+and other critical package management tools which will be broken by
+the new Status field values.  Therefore, the new higher-level tools
+will have to be deployed first.
+
+The new dpkg will declare versioned Breaks against any known
+noncritical package management tools which will be broken by the new
+Status field value.
+
+
+Transition hints for existing packages
+--------------------------------------
+
+When a central (consumer) package defines a directory where other leaf
+(producer) packages may place files and/or directories, and currently
+the producer packages are required to run an «update-consumer» script
+in their postinst:
+ 1. In the relevant policy, define a trigger name which is the name of
+    the directory where the individual files are placed by producer
+    packages.
+ 2. Update the consumer package:
+    * Declare an interest in the trigger.
+    * Edit «update-consumer» so that if it is called without --real
+      it does the following:
+	  if type dpkg-trigger >/dev/null 2>&1 && \
+	     dpkg-trigger name-of-trigger; then
+		exit 0
+	  fi
+      If this fails to cause «update-consumer» to exit, it should do
+      its normal update processing.  Alternatively, if it is more
+      convenient, «update-consumer» could be renamed and supplanted with
+      a wrapper script which conditionally runs the real
+      «update-consumer».
+    * In the postinst, arrange for the new ‘triggered’ invocation to
+      run «update-consumer --real».  The consumer package's postinst
+      will already run «update-consumer» during configuration, and this
+      should be retained and supplemented with the --real option (or
+      changed to call the real script rather than the wrapper).
+ 3. Update the producer packages:
+    * In the postinst, remove the call to «update-consumer».
+    * Change the dependency on consumer to be versioned, specifying a
+      trigger-interested consumer.
+    This can be done at our leisure.  Ideally for loosely coupled
+    packages this would be done only in the release after the one
+    containing the triggers-interested consumer, to facilitate partial
+    upgrades and backports.
+ 4. After all producer packages have been updated according to step 3,
+    «update-consumer» has become an interface internal to the consumer
+    and need no longer be kept stable.  If un-updated producers are
+    still of interest, incompatible changes to «update-consumer» imply
+    a versioned Breaks against the old producers.
+(See also “Transition plan”, below.)
+
+If there are several consumer packages all of which are interested in
+the features provided by producer packages, the current arrangements
+usually involve an additional central switchboard package (eg,
+emacsen-common).  In this case:
+
+ -- NOTE - this part of the transition plan is still a proof of
+           concept and we might yet improve on it
+
+ 1. Define the trigger name.
+ 2. Update the switchboard to have any new functionality needed by the
+    consumers in step 3 (2nd bullet).
+ 3. Update the consumer packages:
+    * Declare an interest in the trigger.
+    * In the postinst, arrange for the new ‘trigger’ invocation to run
+      the compilation/registration process.  This may involve scanning
+      for new or removed producers, and may involve new common
+      functionality from the switchboard (in which case a versioned
+      Depends is needed).
+    * The old interface allowing the switchboard to run
+      compilation/registration should be preserved, including
+      calls to the switchboard to register this consumer.
+ 4. When all consumers have been updated, update the switchboard:
+    * Make the registration scripts called by producers try to
+      activate the trigger and if that succeeds quit without
+      doing any work (as for bullet 2 in the simple case above).
+    * Versioned Breaks, against the old (pre-step-3) consumers.
+ 5. After the switchboard has been updated, producers can be updated:
+    * Remove the calls to the switchboard registration/compilation
+      functions.
+    * Change the dependency on the switchboard to a versioned one,
+      specifying the one which Breaks old consumers.  Alternatively,
+      it may be the case that the switchboard is no longer needed (or
+      not needed for this producer), in which case the dependency on
+      the switchboard can be removed in favour of an appropriate
+      versioned Breaks (probably, identical to that in the new
+      switchboard).
+ 6. After all the producers have been updated, the cruft in the
+    consumers can go away:
+    * Remove the calls to the switchboard's registration system.
+    * Versioned Breaks against old switchboards, or versioned Depends
+      on new switchboards, depending on whether the switchboard is
+      still needed for other common functionality.
+ 7. After all of the producers and consumers have been updated, the
+    cruft in the switchboard can go away:
+    * Remove the switchboard's registration system (but not obviously
+      the common functionality from step 3, discussed above).
+    * Versioned Breaks against pre-step-6 consumers and pre-step-5
+      producers.
+
+
+DISCUSSION
+==========
+
+The activation of a trigger does not record details of the activating
+event.  For example, file triggers do not inform the package of the
+filename.  In the future this might be added as an additional feature,
+but there are some problems with this.
+
+
+Broken producer packages, and error reporting
+---------------------------------------------
+
+Often trigger processing will involve a central package registering,
+compiling or generally parsing some data provided by a leaf package.
+
+If the central package finds problems with the leaf package data it is
+usually more correct for only the individual leaf package to be
+recorded as not properly installed.  There is not currently any way to
+do this and there are no plans to provide one.
+
+The naive approach of giving the postinst a list of the triggering
+packages does not work because this information is not recorded in the
+right way (it might suffer from lacunae); enhancing the bookkeeping
+for this to work would be possible but it is far better simply to make
+the system more idempotent.  See above for the recommended approach.
+
+
+
+
+INTERNALS
+=========
+
+On-disk state
+-------------
+
+A single file /var/lib/dpkg/triggers/File lists all of the filename
+trigger interests in the form
+   /path/to/directory/or/file package
+
+For each explicit trigger in which any package is interested,
+a file /var/lib/dpkg/triggers/<name-of-trigger> is a list of
+the interested packages, one per line.
+
+These interest files are not updated to remove a package just because
+a state change causes it not to be interested in any triggers any more
+- they are updated when we remove or unpack.
+
+For each package which has pending triggers, the status file contains
+a Triggers-Pending field which contains the space-separated names of
+the pending triggers.  For each package which awaits triggers the
+status file contains a Triggers-Awaited field which contains the
+*package* names of the packages whose trigger processing is awaited.
+See “Details - Overview table” above for the invariants which relate
+Triggers-Pending, Triggers-Awaited, and Status.
+
+During dpkg's execution, /var/lib/dpkg/triggers/Unincorp is a list of
+the triggers which have been requested by dpkg-trigger but not yet
+incorporated in the status file.  Each line is a trigger name followed
+by one or more triggering package names.  The triggering package name
+"-" is used to indicate one or more package(s) which did not need to
+await the trigger.
+
+/var/lib/dpkg/triggers/Lock is the fcntl lockfile for the trigger
+system.  Processes hang onto this lock only briefly: dpkg-trigger
+to add new activations, or dpkg to incorporate activations (and
+perhaps when it updates interests).  Therefore this lock is always
+acquired with F_GETLKW so as to serialize rather than fail on
+contention.
+
+
+Processing
+----------
+
+dpkg-trigger updates triggers/Unincorp, and does not read or write the
+status file or take out the dpkg status lock.  dpkg (and dpkg-query)
+reads triggers/Unincorp after reading /var/lib/dpkg/status, and after
+running a maintainer script.  If the status database is opened for
+writing then the data from Unincorp is moved to updates as
+Triggers-Pending and Triggers-Awaited entries and corresponding Status
+changes.
+
+This means that dpkg is guaranteed to reincorporate pending trigger
+information into the status file only 1. when a maintainer script has
+finished, or 2. when dpkg starts up with a view to performing some
+operation.
+
+When a package is unpacked or removed, its triggers control file will
+be parsed and /var/lib/dpkg/triggers/* updated accordingly.
+
+Triggers are run as part of configuration.  dpkg will try to first
+configure all packages which do not depend on packages which are
+awaiting triggers, and then run triggers one package at a time in the
+hope of making useful progress.  (This will involve a new ‘dependtry’
+level in configure.c's algorithm.)  The only constraint on the
+ordering of postinsts is only the normal Depends constraint, so the
+usual Depends cycle breaking will function properly.  See “Cycle
+detection” below regarding cycles in the “A triggers B” relation.
+
+
+Processing - Transitional
+-------------------------
+
+The case where a triggers-supporting dpkg is run for the first time is
+detected by the absence of /var/lib/dpkg/triggers/Unincorp.  When the
+triggers-supporting dpkg starts up without this it will set each
+package's list of pending triggers equal to its interests (obviously
+only for packages which are in ‘installed’ or ‘triggers-pending’).
+This may result in a package going from ‘installed’ to
+‘triggers-pending’ but it will not create the directory at this time.
+Packages marked as triggers-pending in this way will not be scheduled
+for trigger processing in this dpkg run.
+
+dpkg will also at this time create /var/lib/dpkg/triggers if
+necessary, triggers/File, triggers/Unincorp, and the per-trigger
+package lists in /var/lib/dpkg/triggers/<trigger-name>, so that future
+trigger activations will be processed properly.
+
+Only dpkg may create /var/lib/dpkg/triggers and only when it is
+holding the overall dpkg status lock.
+
+dpkg and/or dpkg-deb will be made to reject packages containing
+Triggers-Pending and Triggers-Awaited control file fields, to prevent
+accidents.
+
+
+Cycle detection
+---------------
+
+In addition to dependency cycles, triggers raise the possibility of
+mutually triggering packages - a cycle detectable only dynamically,
+which we will call a “trigger cycle”.
+
+Trigger cycles are detected using the usual hare-and-tortoise
+approach.  Each time after dpkg runs a postinst for triggers, dpkg
+records the set of pending triggers (ie, the set of activated <pending
+package, trigger name> tuples).  If the hare set is a superset of the
+tortoise set, a cycle has been found.
+
+For guaranteed termination, it would be sufficient to declare a cycle
+only when the two sets are identical, but because of the requirement
+to make progress we can cut this short.  Formally, there is supposed
+to be a complete ordering of pending trigger sets satisfying the
+condition that any set of pending triggers is (strictly) greater than
+all its (strict) subsets.  Trigger processing is supposed to
+monotonically decrease the set in this ordering.  (The set elements
+are <package, trigger name> tuples.)
+
+(See “Processing” above for discussion of dependency cycles.)