Tagging images that are dated?

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."

This doesn't really seem like something that needs it's own tag. I can't really think of a reason why I would want to find images that are signed with a date, even in conjunction with other tags.

All of these images are signed with a date and signature, I can't really think of a situation where an artist would date an image but not sign it.

Log said:
This doesn't really seem like something that needs it's own tag. I can't really think of a reason why I would want to find images that are signed with a date, even in conjunction with other tags.

All of these images are signed with a date and signature, I can't really think of a situation where an artist would date an image but not sign it.

What about political satire images? I know the Japanese are not big on that genre, but then you have artist circles like the Tuna Empire.

Political humor is usually heavily dated.

There are the year tags... 2006, 2007, 2008, etc.