Data Validation Question

[Bob Myers]

I'm looking for a custom formula for data validation in a cell. The user is
to be allowed to enter either Yes or No in accordance with the following
logic:

If (True, "No", Or("Yes", "No")) {If a condition is True, he can't do
it; otherwise, he has a choice.}

Respectfully submitted,
Bob Myers

 

[T. Valko]

You should have told us what the condition is.

This will allow only No in B1 if the logical test is TRUE. If the logical
test is FALSE then it will allow only Yes or No.

=IF(logical_test,B1="No",OR(B1="Yes",B1="No"))