It just says that whatever is entered in A1 cannot appear in the area more
than one time.
--
Gary''s Student - gsnu200801


"Louise" wrote:

Hi all

Using the following formula in data validation will avoid the user entering
duplicate entries, however, I don't understand what the A1 is for.... can
anybody explain to me?

Thank you.

=countif($1:$65536,A1)<2