Excel 2003.  I am trying to find a simple subroutine that will allow me to
compare entries in multiple, separate ranges, and to produce a new range
containing the entries that are common to all of the initial ranges (what I
would call an "intersection" set of identifiers).  The entries in each of the
initial ranges contain unique identifiers, which can be compared across
ranges.  I would also like to produce an additional range that contains a
list of all the unique identifiers present in all of the initial ranges
compared (what I would call a "union" set of identifiers).  
I have been doing this by iteratively filtering one range against another,
taking the resultant, and filtering against the next range.  This is tedious.