Undocumented commands in v16

[John Mullahy]

Just a reminder that, as with previous versions, there are numerous "undocumented" commands in v16. These can be unearthed with

help undocumented

While I might quibble with the rationales used to decide what is documentation-worthy, it's nonetheless worth knowing about their existence as some may be valuable (margins, ... generate(...) is the leading example for me).

[Jean-Claude Arbaut]

There are also "very undocumented" commands. I stumbled on fft by mistakenly typing it outside of Mata mode, and I found out at least part of its behavior. It's probably not the only one.

Out of curiosity, it would be nice to have a complete list, at least of the Ado and Mata builtins, even if they are not supposed to be used (for instance I guess the fft command was replaced by the Mata fft function, which seems much faster).

[Nick Cox]

Non-documented is the non-documented term for commands that are not even undocumented. There surely should remain arcane details for the ultra-keen to discover.