I'm confused by the over-kneehighs tag. I thought any socks, stockings, or boots covering past the knee was considered thighhighs and there's plenty of images like that tagged as thighhighs already if I'm not mistaken. If this is to be a separate tag, then there's going to need to be signficant cleanup, and if it is to be a subset of thighhighs then an implication need to be put in place. Using _kneehighs secondary tags like in post #794968 just seems out of place to me, though.
I had made the over-kneehighs tag awhile ago, it was with the intention of having something else to qualify images like post #442307 where the length was significantly shorter than a full thighhigh, but still over the knee. Of the original few I had tagged, I left the thighhigh tag on, since it still fell under what people would expect to find under the thighhighs tag.
post #342378 is maybe a good reference for this, though it's kind of hard to see exactly where the knee is in the illustration. The chart includes thighhighs (as "stockings"), and "over-knee socks". The closest thing to ending on the knee is what it calls "high socks". I don't think they're very common though.
That is why I was looking for the other topic, unless I imagined it. Vocaloid miki for example is indeed wearing over-kneehighs, but due to some tags of zettai ryouiki on her images, thighhighs basically shows up due to implication. So is there a slang term for kneehighs and socks?
I'm not sure why you guys think this is so complicated, it honestly isn't at difficult as you're making it out. The only agreement was that things over the knees would be thighhighs. This does not automatically mean that the over-kneehighs tag shouldn't exist, this just means that it is a subtag of the thighhighs tag.
There are images in which it is very clearly visible that the legwear only barely goes above the knee, such images do have a visible and distinguishable difference from the normal length thighhighs images. It isn't unreasonable to have a tag specifically for such images. In most instances such images will likely be only tagged thighhighs, but for those who wish to be able to place a more specific tag (and as such also search for this specific type of legwear) there then would exist this subtag that could be added and used.