The FairCom RTG OPEN OUTPUT behaved differently than ACUCOBOL / Micro Focus COBOL native file systems if the existing file format was unknown. The OPEN OUTPUT operation failed with an error if the existing file was non-ctree. The logic has been modified to be compliant with these native file systems: if the existing file is non-ctree, it will be overwritten and OPEN OUTPUT will return success.
Note: This is a Behavior Change in FairCom RTG driver to make it compliant to the OPEN OUTPUT standard behavior.