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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css">
+TD {font-family: Verdana,Arial,Helvetica}
+BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em}
+H1 {font-family: Verdana,Arial,Helvetica}
+H2 {font-family: Verdana,Arial,Helvetica}
+H3 {font-family: Verdana,Arial,Helvetica}
+A:link, A:visited, A:active { text-decoration: underline }
+</style><title>Entities or no entities</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td width="180"><a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo" /></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C Logo" /></a><a href="http://www.redhat.com/"><img src="redhat.gif" alt="Red Hat Logo" /></a><div align="left"><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-180x168.gif" alt="Made with Libxml2 Logo" /></a></div></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>The XML C parser and toolkit of Gnome</h1><h2>Entities or no entities</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Developer Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html" style="font-weight:bold">Main Menu</a></li><li><a href="html/index.html" style="font-weight:bold">Reference Manual</a></li><li><a href="examples/index.html" style="font-weight:bold">Code Examples</a></li><li><a href="guidelines.html">XML Guidelines</a></li><li><a href="tutorial/index.html">Tutorial</a></li><li><a href="xmlreader.html">The Reader Interface</a></li><li><a href="ChangeLog.html">ChangeLog</a></li><li><a href="XSLT.html">XSLT</a></li><li><a href="python.html">Python and bindings</a></li><li><a href="architecture.html">libxml2 architecture</a></li><li><a href="tree.html">The tree output</a></li><li><a href="interface.html">The SAX interface</a></li><li><a href="xmlmem.html">Memory Management</a></li><li><a href="xmlio.html">I/O Interfaces</a></li><li><a href="library.html">The parser interfaces</a></li><li><a href="entities.html">Entities or no entities</a></li><li><a href="namespaces.html">Namespaces</a></li><li><a href="upgrade.html">Upgrading 1.x code</a></li><li><a href="threads.html">Thread safety</a></li><li><a href="DOM.html">DOM Principles</a></li><li><a href="example.html">A real example</a></li><li><a href="xml.html">flat page</a>, <a href="site.xsl">stylesheet</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="APIchunk0.html">Alphabetic</a></li><li><a href="APIconstructors.html">Constructors</a></li><li><a href="APIfunctions.html">Functions/Types</a></li><li><a href="APIfiles.html">Modules</a></li><li><a href="APIsymbols.html">Symbols</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li><li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li><li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li><li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li><li><a href="ftp://xmlsoft.org/">FTP</a></li><li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li><li><a href="http://opencsw.org/packages/libxml2">Solaris binaries</a></li><li><a href="http://www.explain.com.au/oss/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://lxml.de/">lxml Python bindings</a></li><li><a href="http://cpan.uwinnipeg.ca/dist/XML-LibXML">Perl bindings</a></li><li><a href="http://libxmlplusplus.sourceforge.net/">C++ bindings</a></li><li><a href="http://www.zend.com/php5/articles/php5-xmlphp.php#Heading4">PHP bindings</a></li><li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li><li><a href="http://libxml.rubyforge.org/">Ruby bindings</a></li><li><a href="http://tclxml.sourceforge.net/">Tcl bindings</a></li><li><a href="https://gitlab.gnome.org/GNOME/libxml2/issues">Bug Tracker</a></li></ul></td></tr></table></td></tr></table></td><td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>Entities in principle are similar to simple C macros. An entity defines an
+abbreviation for a given string that you can reuse many times throughout the
+content of your document. Entities are especially useful when a given string
+may occur frequently within a document, or to confine the change needed to a
+document to a restricted area in the internal subset of the document (at the
+beginning). Example:</p><pre>1 &lt;?xml version="1.0"?&gt;
+2 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
+3 &lt;!ENTITY xml "Extensible Markup Language"&gt;
+4 ]&gt;
+5 &lt;EXAMPLE&gt;
+6 &amp;xml;
+7 &lt;/EXAMPLE&gt;</pre><p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
+its name with '&amp;' and following it by ';' without any spaces added. There
+are 5 predefined entities in libxml2 allowing you to escape characters with
+predefined meaning in some parts of the xml document content:
+<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
+for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
+<strong>&amp;quot;</strong> for the character '"', and
+<strong>&amp;amp;</strong> for the character '&amp;'.</p><p>One of the problems related to entities is that you may want the parser to
+substitute an entity's content so that you can see the replacement text in
+your application. Or you may prefer to keep entity references as such in the
+content to be able to save the document back without losing this usually
+precious information (if the user went through the pain of explicitly
+defining entities, he may have a a rather negative attitude if you blindly
+substitute them as saving time). The <a href="html/libxml-parser.html#xmlSubstituteEntitiesDefault">xmlSubstituteEntitiesDefault()</a>
+function allows you to check and change the behaviour, which is to not
+substitute entities by default.</p><p>Here is the DOM tree built by libxml2 for the previous document in the
+default case:</p><pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
+DOCUMENT
+version=1.0
+ ELEMENT EXAMPLE
+ TEXT
+ content=
+ ENTITY_REF
+ INTERNAL_GENERAL_ENTITY xml
+ content=Extensible Markup Language
+ TEXT
+ content=</pre><p>And here is the result when substituting entities:</p><pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
+DOCUMENT
+version=1.0
+ ELEMENT EXAMPLE
+ TEXT
+ content= Extensible Markup Language</pre><p>So, entities or no entities? Basically, it depends on your use case. I
+suggest that you keep the non-substituting default behaviour and avoid using
+entities in your XML document or data if you are not willing to handle the
+entity references elements in the DOM tree.</p><p>Note that at save time libxml2 enforces the conversion of the predefined
+entities where necessary to prevent well-formedness problems, and will also
+transparently replace those with chars (i.e. it will not generate entity
+reference elements in the DOM tree or call the reference() SAX callback when
+finding them in the input).</p><p><span style="background-color: #FF0000">WARNING</span>: handling entities
+on top of the libxml2 SAX interface is difficult!!! If you plan to use
+non-predefined entities in your documents, then the learning curve to handle
+then using the SAX API may be long. If you plan to use complex documents, I
+strongly suggest you consider using the DOM interface instead and let libxml
+deal with the complexity rather than trying to do it yourself.</p><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html>