Straightforward pipeline

<p:declare-step xml:id="b1-xhtml"
		xmlns:p="http://www.w3.org/ns/xproc">
  <p:input port="parameters" kind="parameter"/>

  <p:xinclude>
    <p:input port="source">
      <p:document href="langspec.xml"/>
    </p:input>
  </p:xinclude>

  <p:validate-with-relax-ng>
    <p:input port="schema">
      <p:document href="../schema/dbspec.rng"/>
    </p:input>
  </p:validate-with-relax-ng>

  <p:xslt>
    <p:input port="stylesheet">
      <p:document href="../style/dbspec.xsl"/>
    </p:input>
  </p:xslt>

  <p:exec command="/Users/ndw/bin/tidy-stream"/>

  <p:store href="langspec.html" method="xhtml"/>
</p:declare-step>