Required Attribute for 4GL

Hello can anyone help me with this problem that I have encountered while developing some programs using informix-4GL In the form specification, I have included a REQUIRED attribute in one of my field. Back in my program, I used the INPUT with a WITHOUT DEFAULTS clause. During runtime, I did not key in any value for that particular field, and the RDS just accept and store a null value into the database for that field. Currently, I am forcing a check on that field to ensure that the user key in a value. But the list of keys is too long and tideous to do likewise. Thanks and best regards