Do pipelines have ports?

I know steps have ports, such as this:

<p:xslt>
  <p:input port="source">
    <p:pipe step="main" port="source"/>
  </p:input>
  <p:input port="stylesheet">
    <p:document href="http://example.com/stylesheets/doc.xsl"/>
  </p:input>
  ...
</p:xslt>

The WD says this explicitly:  ³A p:input identifies an input port for a
step.²

Is it correct to say that pipelines have ports as well, given an example
such as this?

<p:declare-step xmlns:p="http://www.w3.org/ns/xproc">
    <p:input port="source">
        <p:document href="BookStore.xml"/>
    </p:input>
    <p:output port="result"/>
    <p:identity/>
</p:declare-step>

If not, what do you call them?

TIA,

James Garriss
http://garriss.blogspot.com