According to the wiki entry, anonymous is a tag used to describe art posted anonymously
The artist posting the image was not documented, signed, or sealed, and no name was given by the ORIGINAL artist. This is common for some who post to Image boards such as Futaba based sites like *chan. Not to be confused with Unknown Artist which was redistributed by a person without submitting information of the artist.
so it probably should be of the type "artist", and yet the tag's type is "character".
Most likely someone long ago confused it with the anon tag, which is meant to be used for the green "anonymous" character from chans and such.
I would just change it back to the proper type myself, but as a regular user i can't do that once the number of posts using that tag reaches 100 (iirc), which is the case here, so i'd like to ask a mod/admin/whoever to change it.
I can go through the 300-something posts to change ones depicting Anon character to use "anon" instead later.
Also, wouldn't it be less confusing for the future if "anonymous" was changed to "anonymous_artist", and a new "anonymous" tag was created implied to as an alias of "anon" character?
Updated by Furrin Gok