Stefan, the difference is that ERROR can be used to throw any error you need, while FIELDERROR checks the field’s value against the value you provide, then displays an error message containing the field’s name and a message that some value is required or not allowed. It’s really just a shorthand for IF "xxx" <> reqVal THEN error('%1 must be %2', FIELDNAME("xxx"), reqVal); or IF "xxx" = 0 OR '' THEN // yeah, illegal comparison, I know ;-) error('%1 must not be empty', FIELDNAME("xxx")); Good luck - let me know if things work out the way you want [8D]