Ok, here's a few ideas to get the ball rolling - I'm hoping others will jump in and correct/enhance my suggestions.

I've been skimming a few of the recent F/m stories which contain a lot of belittlement of slaves (calling them a slut, teasing them about their genitalita and so on) - does this have a specific term already btw? Looking at those categories the closest is humiliation, which must also encompass other forms of private humiliation, and public humiliation, public nudity and so on. So that is one area that could be expanded. Maybe it also needs a category the opposite of romantic, like "unfeeling", lol.

There are a lot of sexual activities that I think could be added. Obviously we have to draw the line somewhere, but I think anal sex, anal toys and face-sitting (or perhaps forced oral?) are strong candidates for inclusion. They are things I often write about - maybe other authors have noticed other gaps.

We have lactation already. I'm not sure if it's as common but a mirror category for come (i.e. semen) play might be good (does that also have a term for it?). On a side note, I think chastity belt might be better renamed to "sex denial" - I hadn't realised that it encompassed that.

What d'y'all think?