I was just mapping local shops, and one is a pop-up shop. This means the vendor using the space will change over time, but the category of space is fixed. Pop-up enterprises like pop-up shops and pop-up restaurants are fairly common, especially in London, so I think there should be a category for them. There’s even a pop-up mall called Boxpark in Shoreditch, just to indicate the category’s popularity (Boxpark is just labelled as a mall at the moment).
I couldn’t find any mention of pop-ups on the wiki, but I’m too new to consider posting a suggestion myself. Any comments are appreciated.
Maybe you could try the tagging mailing list. New tags and tagging problems are the main topic of that list