We have m and M tags, and we use them. But I see them as explanatory and especially useful for more specialized kinds, like 30040s, so that people can understand what they are seeing in the wild. They're also useful labels for events, in search results. I don't see the value in only having them, tho. I like kinds. Precisely because they are more ambiguous and don't feign exactness. I don't really get the point of NIPs because I just search the repo for a kind number.