I have made a standard roll down table with a name list in alphabetical order
from the validation function in Excel 2003 (not Auto filter). This list has
become so long that it is bothersome to use.

I therefore want to make one more roll down table so that the list can be
split into subcategories, for instance by alphabet og ngeographic region, so
that the oriinal list can get a more handy size. This means that if I click
on "A" in the first list, the next (original) list will only show names
starting ith "A" and so on.

How is this two-step operation performed?