Have just made an Interop DCP with DOM 2.16.55 (not tested in 2.16.56 yet, but don't see anything related in changelog) on Mac OS 10.14.6.

The CPL comes out with MainMarkers:

First reel: FFOC with offset 1
Last reel: LFOC with offset equal to number of frames in last reel - 1

It strikes me these aren't very useful markers, as they don't convey any information beyond "it starts at the start, and ends at the end"!

The odd thing is that when outputting Interop, the "Markers" button is greyed out, so there's no way to set useful markers e.g. for start of end credits. But there's also no way to disable the FFOC/LFOC markers.

Something similar was discussed before (https://www.dcpomatic.com/forum/viewtopic.php?t=1834) but it's unclear to me from that discussion what the upshot was.

Are markers meant to be included in Interop DCPs? If so:

1. Is there any incompatibility risk associated with this?
2. Should it be possible to set other markers at chosen offsets as in SMPTE?
3. Would it be possible to add an option to disable the default markers if you don't want them?