(2021-04-30, 15:19)Orion Pobursky Wrote: Exactly. The mpd extension isn't going away nor will it be wrong to use it. Rather, LDraw.org will only recommend using DAT (for library files) and LDR (for everything else).
Then it sounds like it would be fine either way. The only practical effect I can see is having to change the OMR spec to allow .mpd, but require only .ldr.