The question has been raised here, and I have answered, but the software of this forum is so poor, finding a past information is like searching a needle in a haystack.
AFAIK, there is no format/layout difference between Encore5 and MTDL4 files, the difference which lays in the file extensions is somehow cosmetic.
Don has confirmed here that E6 would handle E5 files, the MTD4 question wasn’t raised yet at that time. He comes on this forum only once in a while.