I couldn't find any official guidelines on this, apologies if it's posted somewhere.
Since characters can't have actual DNP status given to them, I figured that it's a good idea to have the wiki page for the character's tag mention that their owner doesn't want the character posted.
This seems easy to do when art featuring a character has been uploaded in the past and a tag already exists. If someone tries to upload art featuring that character, they would be able to use the tag using auto-complete. Afterwards anyone can visit the tag's wiki and find that art of that character shouldn't be uploaded.
But what should be done when there is no existing tag for a character? In that case the uploader will use the tag for the first time and its name may not match with the name of the wiki page, which makes it sort of pointless.
I'm probably overthinking this, but I'd like to know if this is a good practice and what would be the best way of doing it.