The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" xmlns:test="http://test" version="3.0">
<p:output port="result"/>
<p:declare-step type="test:test">
<p:output port="result" sequence="true">
<p:pipe step="one" port="result"/>
<p:pipe port="result"/>
<p:pipe step="one"/>
<p:pipe step="two"/>
</p:output>
<p:identity name="one">
<p:with-input>
<one/>
</p:with-input>
</p:identity>
<p:identity name="two">
<p:with-input>
<two/>
</p:with-input>
</p:identity>
</p:declare-step>
<test:test/>
<p:wrap-sequence wrapper="wrapper">
<p:with-input>
</p:with-input>
</p:wrap-sequence>
</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="wrapper">The root is not 'wrapper'.</s:assert>
<s:assert test="count(wrapper/*)=4">The root element should have exactly four child.</s:assert>
<s:assert test="wrapper/*[1]/name()='one'">First child is not named 'one'.</s:assert>
<s:assert test="wrapper/*[2]/name()='two'">Second child is not named 'two'.</s:assert>
<s:assert test="wrapper/*[3]/name()='one'">Third child is not named 'one'.</s:assert>
<s:assert test="wrapper/*[4]/name()='two'">Forth child is not named 'two'.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
