The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:choose>
<p:with-input>
<p:inline>
<doc>
<p>Para about XML</p>
</doc>
</p:inline>
</p:with-input>
<p:when test="//p[contains(., 'XML')]">
<p:with-input>
<p:inline>
<doc>
<p>Para about something else</p>
</doc>
</p:inline>
</p:with-input>
<p:identity>
<p:with-input port="source">
<p:inline>
<result>Incorrect</result>
</p:inline>
</p:with-input>
</p:identity>
</p:when>
<p:when test="//p[contains(., 'XML')]">
<p:identity>
<p:with-input port="source">
<p:inline>
<result>Correct</result>
</p:inline>
</p:with-input>
</p:identity>
</p:when>
<p:otherwise>
<p:identity>
<p:with-input port="source">
<p:inline>
<result>Incorrect</result>
</p:inline>
</p:with-input>
</p:identity>
</p:otherwise>
</p:choose>
</p:declare-step>
Schematron validation
<s:schema xmlns="http://www.w3.org/1999/xhtml" xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<s:pattern>
<s:rule context="/">
<s:assert test="/result">Root element is not 'result'.</s:assert>
<s:assert test="/result/text()='Correct'">Text in 'result' is not 'Correct'.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
