As promised. Although I do not pretend to know any top secret information only things that I have noticed or discovered myself over the years. There are some however in QL Heaven who believe in the official QDOS secrets act and have complained bitterly about it over the years. And then there is the dirty washing sometimes found on the ql-users forum and in QLToday.
Any here's one for for starters. The MOVEP instruction was removed from smsqe to improve compatibility with the 68060 processors of the Q60. But if you plan to use Text87plus4 on the Q60 you still need to LRESPR the MOVP4SMSQ60_cde extension as Text87plus4 also has MOVEP instructions.
When smsqe moved to version 3.04 or higher the channel definition block for console channels jumped in size from 304 to 432 bytes without warning.
Thats all for the moment, but more to come.