>
> set firstRequest to (create new request)
> set cell "cellNameA" of firstRequest to "x"
> set secondRequest to (create new request with omitted)
> set cell "cellNameB" of secondRequest to "y"
> find
> tell document 1
> set myResults to every record
> end tell
>
> There's a thing or two wrong with the alternate approach, though. First, it
> doesn't seem to include the secondRequest in its search criteria. I get the
> same results if I leave out the 3rd & 4th lines (i.e. "set secondRequest..."
> and "set cell "cellNameB ..."). Apparently I need to tweak my syntax just a
> little.

The second request works fine for me. But your use of omitted does not work
for me. FWIW this is the way I would do it:

Delete every request
Set NR to (create new request)
Copy "X" to cell "cellnameA" of NR
Set NR to (create new request)
Set omitted of NR to true
Copy "Y" to cell "cellnameA" of NR