1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<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"> 4TD {font-family: Verdana,Arial,Helvetica} 5BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em} 6H1 {font-family: Verdana,Arial,Helvetica} 7H2 {font-family: Verdana,Arial,Helvetica} 8H3 {font-family: Verdana,Arial,Helvetica} 9A:link, A:visited, A:active { text-decoration: underline } 10</style><title>Catalog support</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>Catalog support</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>Main 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">Home</a></li><li><a href="html/index.html">Reference Manual</a></li><li><a href="intro.html">Introduction</a></li><li><a href="FAQ.html">FAQ</a></li><li><a href="docs.html" style="font-weight:bold">Developer Menu</a></li><li><a href="bugs.html">Reporting bugs and getting help</a></li><li><a href="help.html">How to help</a></li><li><a href="downloads.html">Downloads</a></li><li><a href="news.html">Releases</a></li><li><a href="XMLinfo.html">XML</a></li><li><a href="XSLT.html">XSLT</a></li><li><a href="xmldtd.html">Validation & DTDs</a></li><li><a href="encoding.html">Encodings support</a></li><li><a href="catalog.html">Catalog support</a></li><li><a href="namespaces.html">Namespaces</a></li><li><a href="contribs.html">Contributions</a></li><li><a href="examples/index.html" style="font-weight:bold">Code Examples</a></li><li><a href="html/index.html" style="font-weight:bold">API Menu</a></li><li><a href="guidelines.html">XML Guidelines</a></li><li><a href="ChangeLog.html">Recent Changes</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>Table of Content:</p><ol> 11 <li><a href="General2">General overview</a></li> 12 <li><a href="#definition">The definition</a></li> 13 <li><a href="#Simple">Using catalogs</a></li> 14 <li><a href="#Some">Some examples</a></li> 15 <li><a href="#reference">How to tune catalog usage</a></li> 16 <li><a href="#validate">How to debug catalog processing</a></li> 17 <li><a href="#Declaring">How to create and maintain catalogs</a></li> 18 <li><a href="#implemento">The implementor corner quick review of the 19 API</a></li> 20 <li><a href="#Other">Other resources</a></li> 21</ol><h3><a name="General2" id="General2">General overview</a></h3><p>What is a catalog? Basically it's a lookup mechanism used when an entity 22(a file or a remote resource) references another entity. The catalog lookup 23is inserted between the moment the reference is recognized by the software 24(XML parser, stylesheet processing, or even images referenced for inclusion 25in a rendering) and the time where loading that resource is actually 26started.</p><p>It is basically used for 3 things:</p><ul> 27 <li>mapping from "logical" names, the public identifiers and a more 28 concrete name usable for download (and URI). For example it can associate 29 the logical name 30 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p> 31 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be 32 downloaded</p> 33 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p> 34 </li> 35 <li>remapping from a given URL to another one, like an HTTP indirection 36 saying that 37 <p>"http://www.oasis-open.org/committes/tr.xsl"</p> 38 <p>should really be looked at</p> 39 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p> 40 </li> 41 <li>providing a local cache mechanism allowing to load the entities 42 associated to public identifiers or remote resources, this is a really 43 important feature for any significant deployment of XML or SGML since it 44 allows to avoid the aleas and delays associated to fetching remote 45 resources.</li> 46</ul><h3><a name="definition" id="definition">The definitions</a></h3><p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p><ul> 47 <li>the older SGML catalogs, the official spec is SGML Open Technical 48 Resolution TR9401:1997, but is better understood by reading <a href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from 49 James Clark. This is relatively old and not the preferred mode of 50 operation of libxml.</li> 51 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML 52 Catalogs</a> is far more flexible, more recent, uses an XML syntax and 53 should scale quite better. This is the default option of libxml.</li> 54</ul><p></p><h3><a name="Simple" id="Simple">Using catalog</a></h3><p>In a normal environment libxml2 will by default check the presence of a 55catalog in /etc/xml/catalog, and assuming it has been correctly populated, 56the processing is completely transparent to the document user. To take a 57concrete example, suppose you are authoring a DocBook document, this one 58starts with the following DOCTYPE definition:</p><pre><?xml version='1.0'?> 59<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN" 60 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"></pre><p>When validating the document with libxml, the catalog will be 61automatically consulted to lookup the public identifier "-//Norman Walsh//DTD 62DocBk XML V3.1.4//EN" and the system identifier 63"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have 64been installed on your system and the catalogs actually point to them, libxml 65will fetch them from the local disk.</p><p style="font-size: 10pt"><strong>Note</strong>: Really don't use this 66DOCTYPE example it's a really old version, but is fine as an example.</p><p>Libxml2 will check the catalog each time that it is requested to load an 67entity, this includes DTD, external parsed entities, stylesheets, etc ... If 68your system is correctly configured all the authoring phase and processing 69should use only local files, even if your document stays portable because it 70uses the canonical public and system ID, referencing the remote document.</p><h3><a name="Some" id="Some">Some examples:</a></h3><p>Here is a couple of fragments from XML Catalogs used in libxml2 early 71regression tests in <code>test/catalogs</code> :</p><pre><?xml version="1.0"?> 72<!DOCTYPE catalog PUBLIC 73 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 74 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 75<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 76 <public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 77 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 78...</pre><p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are 79written in XML, there is a specific namespace for catalog elements 80"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this 81catalog is a <code>public</code> mapping it allows to associate a Public 82Identifier with an URI.</p><pre>... 83 <rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/" 84 rewritePrefix="file:///usr/share/xml/docbook/"/> 85...</pre><p>A <code>rewriteSystem</code> is a very powerful instruction, it says that 86any URI starting with a given prefix should be looked at another URI 87constructed by replacing the prefix with an new one. In effect this acts like 88a cache system for a full area of the Web. In practice it is extremely useful 89with a file prefix if you have installed a copy of those resources on your 90local system.</p><pre>... 91<delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //" 92 catalog="file:///usr/share/xml/docbook.xml"/> 93<delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML" 94 catalog="file:///usr/share/xml/docbook.xml"/> 95<delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML" 96 catalog="file:///usr/share/xml/docbook.xml"/> 97<delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/" 98 catalog="file:///usr/share/xml/docbook.xml"/> 99<delegateURI uriStartString="http://www.oasis-open.org/docbook/" 100 catalog="file:///usr/share/xml/docbook.xml"/> 101...</pre><p>Delegation is the core features which allows to build a tree of catalogs, 102easier to maintain than a single catalog, based on Public Identifier, System 103Identifier or URI prefixes it instructs the catalog software to look up 104entries in another resource. This feature allow to build hierarchies of 105catalogs, the set of entries presented should be sufficient to redirect the 106resolution of all DocBook references to the specific catalog in 107<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all 108references for DocBook 4.2.1 to a specific catalog installed at the same time 109as the DocBook resources on the local machine.</p><h3><a name="reference" id="reference">How to tune catalog usage:</a></h3><p>The user can change the default catalog behaviour by redirecting queries 110to its own set of catalogs, this can be done by setting the 111<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an 112empty one should deactivate loading the default <code>/etc/xml/catalog</code> 113default catalog</p><h3><a name="validate" id="validate">How to debug catalog processing:</a></h3><p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will 114make libxml2 output debugging information for each catalog operations, for 115example:</p><pre>orchis:~/XML -> xmllint --memory --noout test/ent2 116warning: failed to load external entity "title.xml" 117orchis:~/XML -> export XML_DEBUG_CATALOG= 118orchis:~/XML -> xmllint --memory --noout test/ent2 119Failed to parse catalog /etc/xml/catalog 120Failed to parse catalog /etc/xml/catalog 121warning: failed to load external entity "title.xml" 122Catalogs cleanup 123orchis:~/XML -> </pre><p>The test/ent2 references an entity, running the parser from memory makes 124the base URI unavailable and the the "title.xml" entity cannot be loaded. 125Setting up the debug environment variable allows to detect that an attempt is 126made to load the <code>/etc/xml/catalog</code> but since it's not present the 127resolution fails.</p><p>But the most advanced way to debug XML catalog processing is to use the 128<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load 129catalogs and make resolution queries to see what is going on. This is also 130used for the regression tests:</p><pre>orchis:~/XML -> ./xmlcatalog test/catalogs/docbook.xml \ 131 "-//OASIS//DTD DocBook XML V4.1.2//EN" 132http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 133orchis:~/XML -> </pre><p>For debugging what is going on, adding one -v flags increase the verbosity 134level to indicate the processing done (adding a second flag also indicate 135what elements are recognized at parsing):</p><pre>orchis:~/XML -> ./xmlcatalog -v test/catalogs/docbook.xml \ 136 "-//OASIS//DTD DocBook XML V4.1.2//EN" 137Parsing catalog test/catalogs/docbook.xml's content 138Found public match -//OASIS//DTD DocBook XML V4.1.2//EN 139http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 140Catalogs cleanup 141orchis:~/XML -> </pre><p>A shell interface is also available to debug and process multiple queries 142(and for regression tests):</p><pre>orchis:~/XML -> ./xmlcatalog -shell test/catalogs/docbook.xml \ 143 "-//OASIS//DTD DocBook XML V4.1.2//EN" 144> help 145Commands available: 146public PublicID: make a PUBLIC identifier lookup 147system SystemID: make a SYSTEM identifier lookup 148resolve PublicID SystemID: do a full resolver lookup 149add 'type' 'orig' 'replace' : add an entry 150del 'values' : remove values 151dump: print the current catalog state 152debug: increase the verbosity level 153quiet: decrease the verbosity level 154exit: quit the shell 155> public "-//OASIS//DTD DocBook XML V4.1.2//EN" 156http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd 157> quit 158orchis:~/XML -> </pre><p>This should be sufficient for most debugging purpose, this was actually 159used heavily to debug the XML Catalog implementation itself.</p><h3><a name="Declaring" id="Declaring">How to create and maintain</a> catalogs:</h3><p>Basically XML Catalogs are XML files, you can either use XML tools to 160manage them or use <strong>xmlcatalog</strong> for this. The basic step is 161to create a catalog the -create option provide this facility:</p><pre>orchis:~/XML -> ./xmlcatalog --create tst.xml 162<?xml version="1.0"?> 163<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 164 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 165<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 166orchis:~/XML -> </pre><p>By default xmlcatalog does not overwrite the original catalog and save the 167result on the standard output, this can be overridden using the -noout 168option. The <code>-add</code> command allows to add entries in the 169catalog:</p><pre>orchis:~/XML -> ./xmlcatalog --noout --create --add "public" \ 170 "-//OASIS//DTD DocBook XML V4.1.2//EN" \ 171 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml 172orchis:~/XML -> cat tst.xml 173<?xml version="1.0"?> 174<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \ 175 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 176<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"> 177<public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN" 178 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/> 179</catalog> 180orchis:~/XML -> </pre><p>The <code>-add</code> option will always take 3 parameters even if some of 181the XML Catalog constructs (like nextCatalog) will have only a single 182argument, just pass a third empty string, it will be ignored.</p><p>Similarly the <code>-del</code> option remove matching entries from the 183catalog:</p><pre>orchis:~/XML -> ./xmlcatalog --del \ 184 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml 185<?xml version="1.0"?> 186<!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" 187 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> 188<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/> 189orchis:~/XML -> </pre><p>The catalog is now empty. Note that the matching of <code>-del</code> is 190exact and would have worked in a similar fashion with the Public ID 191string.</p><p>This is rudimentary but should be sufficient to manage a not too complex 192catalog tree of resources.</p><h3><a name="implemento" id="implemento">The implementor corner quick review of the 193API:</a></h3><p>First, and like for every other module of libxml, there is an 194automatically generated <a href="html/libxml-catalog.html">API page for 195catalog support</a>.</p><p>The header for the catalog interfaces should be included as:</p><pre>#include <libxml/catalog.h></pre><p>The API is voluntarily kept very simple. First it is not obvious that 196applications really need access to it since it is the default behaviour of 197libxml2 (Note: it is possible to completely override libxml2 default catalog 198by using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to 199plug an application specific resolver).</p><p>Basically libxml2 support 2 catalog lists:</p><ul> 200 <li>the default one, global shared by all the application</li> 201 <li>a per-document catalog, this one is built if the document uses the 202 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is 203 associated to the parser context and destroyed when the parsing context 204 is destroyed.</li> 205</ul><p>the document one will be used first if it exists.</p><h4>Initialization routines:</h4><p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be 206used at startup to initialize the catalog, if the catalog should be 207initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs() 208should be called before xmlInitializeCatalog() which would otherwise do a 209default initialization first.</p><p>The xmlCatalogAddLocal() call is used by the parser to grow the document 210own catalog list if needed.</p><h4>Preferences setup:</h4><p>The XML Catalog spec requires the possibility to select default 211preferences between public and system delegation, 212xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and 213xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should 214be forbidden, allowed for global catalog, for document catalog or both, the 215default is to allow both.</p><p>And of course xmlCatalogSetDebug() allows to generate debug messages 216(through the xmlGenericError() mechanism).</p><h4>Querying routines:</h4><p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic() 217and xmlCatalogResolveURI() are relatively explicit if you read the XML 218Catalog specification they correspond to section 7 algorithms, they should 219also work if you have loaded an SGML catalog with a simplified semantic.</p><p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but 220operate on the document catalog list</p><h4>Cleanup and Miscellaneous:</h4><p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is 221the per-document equivalent.</p><p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the 222first catalog in the global list, and xmlCatalogDump() allows to dump a 223catalog state, those routines are primarily designed for xmlcatalog, I'm not 224sure that exposing more complex interfaces (like navigation ones) would be 225really useful.</p><p>The xmlParseCatalogFile() is a function used to load XML Catalog files, 226it's similar as xmlParseFile() except it bypass all catalog lookups, it's 227provided because this functionality may be useful for client tools.</p><h4>threaded environments:</h4><p>Since the catalog tree is built progressively, some care has been taken to 228try to avoid troubles in multithreaded environments. The code is now thread 229safe assuming that the libxml2 library has been compiled with threads 230support.</p><p></p><h3><a name="Other" id="Other">Other resources</a></h3><p>The XML Catalog specification is relatively recent so there isn't much 231literature to point at:</p><ul> 232 <li>You can find a good rant from Norm Walsh about <a href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the 233 need for catalogs</a>, it provides a lot of context information even if 234 I don't agree with everything presented. Norm also wrote a more recent 235 article <a href="http://wwws.sun.com/software/xml/developers/resolver/article/">XML 236 entities and URI resolvers</a> describing them.</li> 237 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML 238 catalog proposal</a> from John Cowan</li> 239 <li>The <a href="http://www.rddl.org/">Resource Directory Description 240 Language</a> (RDDL) another catalog system but more oriented toward 241 providing metadata for XML namespaces.</li> 242 <li>the page from the OASIS Technical <a href="http://www.oasis-open.org/committees/entity/">Committee on Entity 243 Resolution</a> who maintains XML Catalog, you will find pointers to the 244 specification update, some background and pointers to others tools 245 providing XML Catalog support</li> 246 <li>There is a <a href="buildDocBookCatalog">shell script</a> to generate 247 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/ 248 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on 249 the resources found on the system. Otherwise it will just create 250 ~/xmlcatalog and ~/dbkxmlcatalog and doing: 251 <p><code>export XML_CATALOG_FILES=$HOME/xmlcatalog</code></p> 252 <p>should allow to process DocBook documentations without requiring 253 network accesses for the DTD or stylesheets</p> 254 </li> 255 <li>I have uploaded <a href="ftp://xmlsoft.org/libxml2/test/dbk412catalog.tar.gz">a 256 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems 257 to work fine for me too</li> 258 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog 259 manual page</a></li> 260</ul><p>If you have suggestions for corrections or additions, simply contact 261me:</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> 262