Filter ( Self ; "abcdefghijklmnopqrstuvwxyz" & Upper ( "abcdefghijklmnopqrstuvwxyz" ) & "_" ) = Self
This can be set up on the validation tab in field options.
Thanks Phil, this works like a charm. However, the validation requires the user to "revert all changes to this record since it was last entered" instead of just clearing out that one field. I don't want the users to have to start the entire record all over again.
Yes but it's what you asked for.
I'd use the OnObjectValidate script trigger to run a script that uses this same test. When an invalid name is entered, you script can display the message you want them to see with the button options that make sense for your data entry context.
Yes, I'm glad to have a better understanding of how the field validation works, and how to build the filtering calculation.
I hadn't seen the script triggering feature before (still learning V12) , and it works better in this case using the same filter and then an added step that clears the field for correct entry.
Thank you so much for your speedy replies!