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+<!-- doc/src/sgml/README.links -->
+
+Linking within DocBook documents can be confusing, so here is a summary:
+
+
+Intra-document Linking
+----------------------
+
+<xref>
+	use to get chapter/section number from the title of the target
+	link, or xreflabel if defined at the target, or refentrytitle if target
+        is a refentry;  has no close tag
+	http://www.oasis-open.org/docbook/documentation/reference/html/xref.html
+
+linkend=
+	controls the target of the link/xref, required
+
+endterm=
+	for <xref>, allows the text of the link/xref to be taken from a
+	different link target title
+
+<link>
+	use to supply text for the link, only uses linkend, requires </link>
+	http://www.oasis-open.org/docbook/documentation/reference/html/link.html
+
+
+External Linking
+----------------
+
+<ulink>
+	like <link>, but uses a URL (not a document target);  requires
+	</ulink>; if no text is specified, the URL appears as the link
+	text
+	http://www.oasis-open.org/docbook/documentation/reference/html/ulink.html
+
+url=
+	used by <ulink> to specify the URL, required
+
+
+Guidelines
+----------
+
+- For an internal link, if you want to supply text, use <link>, else
+  <xref>.
+
+- Specific nouns like GUC variables, SQL commands, and contrib modules
+  usually have xreflabels.
+
+- For an external link, use <ulink>, with or without link text.