s

<pre>
   <code>(@Item)</code>
</pre>

<p>The list of generator clauses is

<pre>
      ((nr +Item @Nr) (nm +Item @Nm) (pr +Item @Pr))
</pre>

<p>The filter clauses are

<pre>
         (range @Nr @Item nr)
         (part @Nm @Item nm)
         (range @Pr @Item pr)
</pre>


<p><hr>
<h2><a id="univar">Unification Variables</a></h2>

<p>As stated above, the first argument to <code>select</code> should be a list
of variables. These variables communicate values (via <code><a
href="refU.html#unify">unify</a></c