No doubt this has been addressed before but I can't find it. Will someone point me to a "user friendly" script for a data entry validation failure. (504 error capture. Custom dialog. Choice, allow or abort.)

Field validation is done at the "Define Fields" level, in the field options.

You can simulate field validation using a script, but this is an interface things and not real validation. (Field-level validation won't let invalid data be entered into the database. Interface-level validations does.)

You'll usually be using IF statements with IsEmpty() and other functions to display custom dialogs.

I usually go a step further and use a loop:

Go to Layout [ data entry layout ]

Loop

Pause script

Exit loop if [ not isempty( field1 ) and not isempty( field2 ) etc]

Beep

Show Custom dialog[ message about which fields are empty ]

End Loop