Create a list of valid model numbers ... say in Column A of Sheet3 ... and
then validate using:

=if(ISNA(Match(B2,Sheet3!A:A,0)),"Invalid Model number","")

B2 contains model number


If you place this formula in adjacent cell e.g. C2, then message "Invalid
Model number" will appear if the entry in B2 is not found in column A of
Sheet3; if model is valid, no message is produced.

Is this an exceptable solution?

"Mike Smith NC" wrote:

"This validates the values before the 8-part model number is created. Is
that what you're looking for? Or do you need to further validate the
resulting combination against a list of model numbers? "

I need to further validate the resulting combination against a list of model
numbers. Any help?