<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" xmlns:px="http://www.daisy.org/ns/pipeline/xproc" type="px:select-by-position" exclude-inline-prefixes="#all" version="1.0">
<p:input port="source" sequence="true" primary="true"/>
<p:option name="position" required="true"/>
<p:output port="matched" sequence="true" primary="true"/>
<p:output port="not-matched" sequence="true">
<p:pipe step="split-sequence" port="not-matched"/>
</p:output>
<p:split-sequence name="split-sequence">
<p:with-option name="test" select="concat('position()=number(', $position,')')">
<p:empty/>
</p:with-option>
</p:split-sequence>
</p:declare-step>