COBOL pgm to display DDS screen and update a record

How are screens generally handled when writing COBOL to update a record via a DDS screen.

Specifically regarding I, O, or B fields (Input, Output, or Both)

It seems that only "B" works satisfactorily. I thought that I had some "O" fields interspersed with "B" fields working pretty well. I was moving SCREEN-I fields to SCREEN-o fields after every READ from the screen, and reverse after a WRITE.

However it still seems to mess up occasionally, as the screen buffer is mapped very differently for "I" and "O" fields.

The only way I have gotten screen updates to work reliably is to strictly use "B" fields only, and never use "O" fields for updates anyways.

Designating all fields as "B" means that fields in the buffer will stay put - instead of hopping around to different locations before and after the screen I-O.

Do others follow this method? Or is there a way to designate a field as "O" when other fields are "B"?



(A downside of designating "O" fields as "B" is that they are not protected and also show underlines, so each one must be conditioned to unprotect & remove underlines, which is more junk code to get around this issue.)


Thanks!