Sankaku Channel/[Question] Self-Tagging?

As the title says, is self-tagging allowed?

I've come across a tag, kodansha, which is less affiliated with art or works in particular--it just seems to be a tag made by a user (who to my knowledge remains unknown). This tag appears at first to be a collection of loli-related works, of characters that do not share publishers or artists and very rarely there are non-loli-related works that cut a contradiction in the tagging chain. The further the tag goes back, however, the older the tagged articles become and the more diverse they become from each other as well. The only real tie for the older pictures is that they're all of popular characters and manga.

I'm not sure who created the tag, but I am almost certain that there is no meaning behind the word "kodansha" unless broken down into base letters and taken direct arrangement meaning. This is literally, as can be seen, just someone's personal tag to organize what they didn't want to put into their favorites for risk of cluttering.

This tag is from gelbooru, or even danbooro.
Maybe it has some meaning.
http://gelbooru.com/index.php?page=wiki&s=list&search=kodansha
But, since i dont have account there, and too lazy to create...

It's a Japanese publisher. Think Weekly Shonen Magazine and Nakayoshi.
I'm 100% sure I was the one to create the tag, but people are certainly using it incorrectly.