This is an early version of the specification. - Jonathan Borden, December 31,2000
Note: you are looking at the actual XML Catalog for the "http://www.openhealth.org/XMLCatalog/" namespace.
This proposal defines a format for an XML Catalog. An XML Catalog serves as a text description of an XML Namespace [1] and includes links to resources associated with the namespace such as schemata. An XML Catalog may also map Formal Public Identifiers into System Identifiers defined as URI references [2]. It is expected that an XML Catalog will be returned on resolving a namespace URI.
The format of an XML Catalog is XHTML [3]. Links are defined as XLinks [4] originating from LINK elements within the XHTML header.
<!ELEMENT link -- a media-independent link --> <!ATTLIST link %attrs; -- %coreattrs, %i18n, %events -- charset %Charset; #IMPLIED -- char encoding of linked resource -- href %URI; #IMPLIED -- URI for linked resource -- hreflang %LanguageCode; #IMPLIED -- language code -- type %ContentType; #IMPLIED -- advisory content type -- rel %LinkTypes; #IMPLIED -- forward link types -- rev %LinkTypes; #IMPLIED -- reverse link types -- media %MediaDesc; #IMPLIED -- for rendering on these media -- xlink:type (simple) #FIXED "simple" xlink:role CDATA #IMPLIED xlink:arcrole CDATA #IMPLIED xlink:title CDATA #IMPLIED xlink:href CDATA #REQUIRED public CDATA #IMPLIED -- public identifier version CDATA #IMPLIED >
An example:
<html xmlns="http://www.openhealth.org/XMLCatalog/"
xmlns:xcat="http://www.openhealth.org/XMLCatalog/">
<head>
<link type="text/xml-dtd"
rel="alternate"
xlink:type="simple"
xlink:role="http://www.w3.org/tr/xhtml1/DTD/xhtml1-strict.dtd"
xlink:title="XHTML1 Strict DTD"
xlink:arcrole="http://www.w3.org/tr/xhtml1"
xlink:href="xcat-xhtml1-strict.dtd"
public="-//XML Catalog//DTD XHTML Strict 1.0//EN"
version="1.0" />
<link type="text/xml-dtd"
rel="alternate"
xlink:type="simple"
xlink:role="http://www.w3.org/tr/xhtml1/DTD/xhtml1-transitional.dtd"
xlink:title="XHTML1 Transitional DTD"
xlink:arcrole="http://www.w3.org/tr/xhtml1"
xlink:href="xcat-xhtml1-transitional.dtd"
public="-//XML Catalog//DTD XHTML Transitional 1.0//EN"
version="1.0" />
<link type="text/xml-dtd"
rel="alternate"
xlink:type="simple"
xlink:role="http://www.w3.org/tr/xhtml1/DTD/xhtml1-frameset.dtd"
xlink:title="XHTML1 Frameset DTD"
xlink:arcrole="http://www.w3.org/tr/xhtml1"
xlink:href="xcat-xhtml1-frameset.dtd"
public="-//XML Catalog//DTD XHTML Frameset 1.0//EN"
version="1.0" />
<link type="text/xml-dtd"
rel="alternate"
xlink:type="simple"
xlink:arcrole="http://www.w3.org/tr/xhtml11"
xlink:href="xcat-xhtml11.dtd"
public="-//XML Catalog//DTD XHTML 1.1//EN"
version="1.1" />
<link
type="application/xml"
rel="alternate"
xlink:type="simple"
xlink:title="XML Schema"
xlink:arcrole="http://www.w3.org/2000/10/XMLSchema"
xlink:href="xcat-xhtml1.xsd"
public="-//XML Catalog//XSD XHTML 1.0//EN"
/>
<link
type="application/rdf+xml"
rel="alternate"
xlink:type="simple"
xlink:title="RDF Schema"
xlink:arcrole="http://www.w3.org/2000/01/rdf-schema"
xlink:href="http://www.openhealth.org/XMLCatalog/xcat-schema.rdfs"
public="-//XML Catalog//RDFS XML Catalog 1.0//EN"
/>
<link
type="application/SGML-Open-Catalog"
rel="alternate"
xlink:type="simple"
xlink:title="OASIS-Catalog"
xlink:arcrole="http://www.oasis-open.org/html/a401.htm"
xlink:href="xcat-xhtml.soc"
public="-//XML Catalog//SOC XCAT XHTML 1.0//EN"
/>
</head>
<body>...description goes here ...</body>
</html>
The value of the "type" attribute contains a content type.
The value of the "public" attribute contains an optional formal public identifier.
The value of the "version" attribute.
The xlink:role of the link can be used to distinguish among related schemata such as for strict, transitional and frameset
The xlink:arcrole references a schema defining the referenced document, e.g. xhtml, XSD, RDF Schema
The xlink:href contains a mandatory URI referencing the target document