Hi. As far as I remember after 40 years, talkback (TB) is when the engineer talks to the musicians via headphones and therefore Return Talkback (RTB) is when the musicians in the live room talk back to the control room, normally via the Listen mic (s).
Not too sure what switched or unswitched TB is about so, maybe take a picture of your patchbay (which console do you have) and/or connector list for that pinout.
MD was originally intended as a send to the Musical Director (elsewhere in the studio) so the Engineer could talk to them and should be a separate issue.
Hope this helps for now and I would be interested in any other comments for reasons I will explain later. Jim Lassen, wiring moderator on here and worked at SSL from 1980-87.
Maybe rename your post as something to do with talkback as opposed to just Patch Points so people can find it quickly!