Here's an example from their web page:
<pipeline xmlns="http://www.w3.org/2002/02/xml-pipeline"
xml:base="http://example.org/">
<param name="target" select="'result'"/>
<processdef name="xinclude.p" definition="org.example.xml.Xinclude"/>
<processdef name="validate.p" definition="org.example.xml.XmlSchema"/>
<processdef name="transform.p" definition="org.example.xml.XSLT"/>
<process id="p1" type="xinclude.p">
<input name="document" label="myfile.xml"/>
<output name="result" label="xresult"/>
</process>
<process id="p2" type="validate.p">
<input name="document" label="xresult"/>
<input name="schema" label="someschema.xsd"/>
<output name="result" label="valid"/>
<error name="invalid" label="#invalidDocument"/>
</process>
<process id="p3" type="transform.p">
<input name="stylesheet" label="mystyle.xsl"/>
<input name="document" label="valid"/>
<output name="result" label="result"/>
<param name="chunk">0</param>
</process>
<document name="invalidDocument">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Failure!</title>
</head>
<body>
<h1>Your job failed because the document is invalid.</h1>
</body>
</html>
</document>
</pipeline>