referred by item #2 can be found by the generator clause

<pre>
(nr +Item @Nr (itm +Pos))
</pre>

<p>and all positions sold in 2007 can be found by

<pre>
(dat +Ord @Year pos)
</pre>

<p>However, the combination of both generator clauses

<pre>
(select (@Pos)
   ((nr +Item @Nr (itm +Pos)) (dat +Ord @Year pos)) )
</pre>

<p>will probably generate too many results, namely all positions with item #2
<u>OR</u> from the year 2007. Thus, we need two filter clauses. With them, the
full search expression will be:

