Re: xtvd grouping problem (I think)

    for each search item
        find the set of programs which have that item
        convert this to the set of schedule items which have those programs
        for each in the schedule set
            sort by time
            report the show information.

<xsl:for-each $progSet/items[@item=@search]/@prog>
    <xsl:variable name="prog" select="@prog" />
     <xsl:for-each $scheduleSet[@prog = $prog]/@prog>
       <xsl:sort select="@time" />
       <xsl:value-of select="@showInfo"
     </xsl:for-each>
  </xsl:for-each>

Given a variable $progSet which has a bunch of <programs> in it, how
do I define a $schedSet which has only <schedule> items containing
@program ids from $progSet?

I've gotten as far as
<xsl:variable name="schedSet" select="//schedule[@program . . {sound
of screeching brakes}? />

Please excuse where I've strayed from proper XSLT vocabulary; I hope
my intent is clear enough despite such lapses of inexperience.