H'mm I didn;t think schematron was quite as extensible as this. I have been 
using the schema below (I would use an attachment but I'm not sure if thats 
ok on this list) as the definition of where extensibility is allowed. Your 
example below would not be schema valid (actually in checking this I also 
note that using a <sch:name/> inside a <diagnostic> is also invalid - and I 
do this a fair bit -- oops).

Am I using an out-of-date schema ??

Cheers

Fraser.

<?xml version="1.0" encoding="UTF-8"?>
<!-- schemaVersion of 2001/02/15 -->
<xs:schema xmlns:sch="http://www.ascc.net/xml/schematron" 
xmlns="http://www.ascc.net/xml/schematron" 
xmlns:xs="http://www.w3.org/2001/XMLSchema" 
targetNamespace="http://www.ascc.net/xml/schematron" version="+//IDN 
sinica.edu.tw//SGML W3C XML Schema for Schematron 1.5//EN">
	<xs:import namespace="http://www.w3.org/XML/1998/namespace" 
schemaLocation="http://www.w3.org/2001/xml.xsd">
		<xs:annotation>
			<xs:documentation>
       		Get access to the xml: attribute groups for xml:lang
     		</xs:documentation>
		</xs:annotation>
	</xs:import>
	<xs:annotation>
		<xs:documentation 
source="http://www.ascc.net/xml/resource/schematron/schematron.html" 
xml:lang="en"/>
	</xs:annotation>
	<xs:element name="active">
		<xs:complexType mixed="true">
			<xs:choice minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="sch:dir"/>
				<xs:element ref="sch:emph"/>
				<xs:element ref="sch:span"/>
			</xs:choice>
			<xs:attribute name="pattern" type="xs:IDREF" use="required"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="assert">
		<xs:complexType mixed="true">
			<xs:choice minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="sch:name"/>
				<xs:element ref="sch:emph"/>
				<xs:element ref="sch:dir"/>
				<xs:element ref="sch:span"/>
				<xs:any namespace="##other" processContents="lax"/>
			</xs:choice>
			<xs:attribute name="test" type="xs:string" use="required"/>
			<xs:attribute name="role" type="xs:NMTOKEN"/>
			<xs:attribute name="id" type="xs:string"/>
			<xs:attribute name="diagnostics" type="xs:IDREFS"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
			<xs:attribute name="subject" type="xs:string" default="."/>
			<xs:attribute ref="xml:lang"/>
			<xs:anyAttribute namespace="##other" processContents="lax"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="diagnostic">
		<xs:complexType mixed="true">
			<xs:choice minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="sch:value-of"/>
				<xs:element ref="sch:emph"/>
				<xs:element ref="sch:dir"/>
				<xs:element ref="sch:span"/>
				<xs:any namespace="##other" processContents="lax"/>
			</xs:choice>
			<xs:attribute name="id" type="xs:ID" use="required"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
			<xs:attribute ref="xml:lang"/>
			<xs:anyAttribute namespace="##other" processContents="lax"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="diagnostics">
		<xs:complexType>
			<xs:sequence>
				<xs:element ref="diagnostic" minOccurs="0" maxOccurs="unbounded"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
	<xs:element name="dir">
		<xs:complexType>
			<xs:simpleContent>
				<xs:extension base="xs:string">
					<xs:attribute name="value">
						<xs:simpleType>
							<xs:restriction base="xs:NMTOKEN">
								<xs:enumeration value="ltr"/>
								<xs:enumeration value="rtl"/>
							</xs:restriction>
						</xs:simpleType>
					</xs:attribute>
				</xs:extension>
			</xs:simpleContent>
		</xs:complexType>
	</xs:element>
	<xs:element name="emph" type="xs:string"/>
	<xs:element name="extends">
		<xs:complexType>
			<xs:attribute name="rule" type="xs:string" use="required"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="key">
		<xs:complexType>
			<xs:attribute name="name" type="xs:NMTOKEN" use="required"/>
			<xs:attribute name="path" type="xs:string" use="required"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="name">
		<xs:complexType>
			<xs:attribute name="path" type="xs:string" default="."/>
		</xs:complexType>
	</xs:element>
	<xs:element name="ns">
		<xs:complexType>
			<xs:attribute name="uri" type="xs:anyURI" use="required"/>
			<xs:attribute name="prefix" type="xs:NCName"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="p">
		<xs:complexType mixed="true">
			<xs:choice minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="sch:dir"/>
				<xs:element ref="sch:emph"/>
				<xs:element ref="sch:span"/>
			</xs:choice>
			<xs:attribute name="id" type="xs:string"/>
			<xs:attribute name="class" type="xs:string"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
			<xs:attribute ref="xml:lang"/>
			<xs:anyAttribute namespace="##other" processContents="lax"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="pattern">
		<xs:complexType>
			<xs:sequence>
				<xs:element ref="p" minOccurs="0" maxOccurs="unbounded"/>
				<xs:element ref="sch:rule" maxOccurs="unbounded"/>
			</xs:sequence>
			<xs:attribute name="name" type="xs:string" use="required"/>
			<xs:attribute name="see" type="xs:anyURI"/>
			<xs:attribute name="id" type="xs:string"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="phase">
		<xs:complexType>
			<xs:sequence>
				<xs:element ref="sch:p" minOccurs="0" maxOccurs="unbounded"/>
				<xs:element ref="sch:active" maxOccurs="unbounded"/>
			</xs:sequence>
			<xs:attribute name="id" type="xs:string" use="required"/>
			<xs:attribute name="fpi" type="xs:string"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="report">
		<xs:complexType mixed="true">
			<xs:choice minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="sch:name"/>
				<xs:element ref="sch:emph"/>
				<xs:element ref="sch:dir"/>
				<xs:element ref="sch:span"/>
				<xs:any namespace="##other" processContents="lax"/>
			</xs:choice>
			<xs:attribute name="test" type="xs:string" use="required"/>
			<xs:attribute name="role" type="xs:NMTOKEN"/>
			<xs:attribute name="id" type="xs:string"/>
			<xs:attribute name="diagnostics" type="xs:IDREFS"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
			<xs:attribute name="subject" type="xs:string" default="."/>
			<xs:attribute ref="xml:lang"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="rule">
		<xs:complexType>
			<xs:choice maxOccurs="unbounded">
				<xs:element ref="sch:assert"/>
				<xs:element ref="sch:report"/>
				<xs:element ref="sch:key"/>
				<xs:element ref="sch:extends"/>
			</xs:choice>
			<xs:attribute name="context" type="xs:string"/>
			<xs:attribute name="abstract" type="xs:boolean" default="false"/>
			<xs:attribute name="role" type="xs:NMTOKEN"/>
			<xs:attribute name="id" type="xs:string"/>
		</xs:complexType>
	</xs:element>
	<xs:element name="schema">
		<xs:complexType>
			<xs:sequence>
				<xs:element ref="sch:title" minOccurs="0"/>
				<xs:element ref="sch:ns" minOccurs="0" maxOccurs="unbounded"/>
				<xs:element ref="sch:p" minOccurs="0" maxOccurs="unbounded"/>
				<xs:element ref="sch:phase" minOccurs="0" maxOccurs="unbounded"/>
				<xs:element ref="sch:pattern" maxOccurs="unbounded"/>
				<xs:element ref="sch:p" minOccurs="0" maxOccurs="unbounded"/>
				<xs:element ref="sch:diagnostics" minOccurs="0"/>
			</xs:sequence>
			<xs:attribute name="id" type="xs:ID"/>
			<xs:attribute name="fpi" type="xs:string"/>
			<xs:attribute name="schemaVersion" type="xs:string"/>
			<xs:attribute name="defaultPhase" type="xs:string"/>
			<xs:attribute name="icon" type="xs:anyURI"/>
			<xs:attribute name="ns" type="xs:anyURI"/>
			<xs:attribute name="version" type="xs:string" default="1.5"/>
			<xs:attribute ref="xml:lang"/>
			<xs:anyAttribute namespace="##other" processContents="lax"/>
		</xs:complexType>
		<xs:unique name="assertId">
			<xs:selector xpath="sch:pattern/sch:rule/sch:assert"/>
			<xs:field xpath="@id"/>
		</xs:unique>
		<xs:unique name="reportId">
			<xs:selector xpath="sch:pattern/sch:rule/sch:report"/>
			<xs:field xpath="@id"/>
		</xs:unique>
		<xs:unique name="ruleId">
			<xs:selector xpath="sch:pattern/sch:rule"/>
			<xs:field xpath="@id"/>
		</xs:unique>
		<xs:unique name="patternId">
			<xs:selector xpath="sch:pattern"/>
			<xs:field xpath="@id"/>
		</xs:unique>
		<xs:unique name="pId">
			<xs:selector xpath=".//sch:p"/>
			<xs:field xpath="@id"/>
		</xs:unique>
		<xs:key name="phaseId">
			<xs:selector xpath="sch:phase"/>
			<xs:field xpath="@id"/>
		</xs:key>
		<xs:keyref name="activePattern" refer="patternId">
			<xs:selector xpath="sch:phase/sch:active"/>
			<xs:field xpath="@pattern"/>
		</xs:keyref>
		<xs:keyref name="extendsRule" refer="ruleId">
			<xs:selector xpath="sch:pattern/sch:rule/sch:extends"/>
			<xs:field xpath="@rule"/>
		</xs:keyref>
		<xs:keyref name="defaultPhase" refer="phaseId">
			<xs:selector xpath="."/>
			<xs:field xpath="@defaultPhase"/>
		</xs:keyref>
		<!-- Define the identity constraints -->
	</xs:element>
	<xs:element name="span">
		<xs:complexType>
			<xs:simpleContent>
				<xs:extension base="xs:string">
					<xs:attribute name="class" type="xs:string"/>
				</xs:extension>
			</xs:simpleContent>
		</xs:complexType>
	</xs:element>
	<xs:element name="title">
		<xs:complexType mixed="true">
			<xs:choice minOccurs="0" maxOccurs="unbounded">
				<xs:element ref="sch:dir"/>
			</xs:choice>
		</xs:complexType>
	</xs:element>
	<xs:element name="value-of">
		<xs:complexType>
			<xs:attribute name="select" type="xs:string" use="required"/>
		</xs:complexType>
	</xs:element>
</xs:schema>


>From: Rick Jelliffe <rjelliffe@a...>
>To: Fraser Goffin <goffinf@h...>
>CC: xml-dev@l...
>Subject: Re: [xml-dev] Status of ISO Schematron
>Date: Mon, 13 Feb 2006 16:00:38 +1100
>
>Fraser Goffin wrote:
>
>>When you say 'extension elements' do you mean use your own custom 
>>elements/attributes where the schemaTron schema provides for 
>>extensibility, or are you talking about something else entirely ?
>
>Schematron allows foreign-namespace elements and attributes everywhere 
>IIRC.
>
>So you while you cannot change the rule semantics, you can certainly add 
>extra annotating
>capabilities. For example, you could add
>
><sch:rule  context="date"/>
>  <sch:assert  test="string-length(.) &gt; 8">A date should be dd/mm/yyyy 
>format</sch:assert>
>  <my:mailto to="mcguffin@g..." sj="Someone has used the date 
>element!" />
>  ...
></sch:rule>
>
>ISO Schematron also has a flag facility, where  named flags can be set by 
>assertion failures.
>These give a standard way to extract and arbitrary number boolean facts 
>about a document wthout adding any output-specific information, or requring 
>messages to have a particular format that gets reparsed, etc.
>
>Cheers
>Rick Jelliffe