Hi

An example for column A, the formatting starts from A1
=(LEFT($A1,3)="PR-")

Whe you also need all entries to be unique, then
=AND(LEFT($A1,3)="PR-",COUNTIF($A:$A,$A1)<2)


Arvi Laaneemts


"ron" wrote in message
...
What formula should I enter into Category "Custom" of Validatioan to force
user to begin character string with "PR-"? Desired result is "PR-001". I
don't want user to have option to enter "001" or "002", etc., without the
"PR-". Nor do I want them to be able to enter "DR-001".