I was just going through maon's Pixiv page (he's pretty awesome with Copic and pen) and noted that he signs and dates most everything he does. Now, we have signature, but should we tag things that have dates on them, too? I saw that there was a date tage and was using it, but then I realised "Oh wait, wrong sense of the word!"
Maybe timestamp (with all of its one post) could be bullied into this role or something else? I sort of feel like a timestamp is a little different from a simple date; to me, it indicates that it was added mechanically, like a watermark. On the other hand, I'm not at all sure what this tag would be called. Another issues that comes to mind is images that have a date on them, but not necessarily in the sense of "on this date, at this time, this work was completed."
Updated by jjj14