>If a table has OPTIMISTIC ROW BUFFERING how can the system check if a record is open (i.e. being displayed on someonese screen but not necessarily being changed)?
>
>Unless someone changes data, the record is not locked so RLOCK() does not help.
>
>I am looking for something like USED() but relating to records (not tables.)

You could RLOCK the record explicitly everywhere, so after one user has RLOCKed it, the other user tries, and can't.