Along with the flat shelf and device reduction, watch the direction that's facing the rim and when also present on the bust I would suspect MD.
Found its best to double check against known varieties anyways, because some DD can show similar traits, but not this time at least against the 1DO-001.
If you check 1DO-020 is a good example that seems to face the rim. But you see its not flat like and shows definite separation.
The reverse devices are beginning to merge with fields indicating die wear. Thanks, Doug.