No fabric on the wing of a Zero. It sometimes appears that way due to the "oil canning" of the very thin guage metal used by the Japanes to keep the weight of the Zero to a minimum. This is true of many Japanese fighters of the period. What I'm finding in my research on the Hellcat is that both raised and flush rivets were used and it's probably the same deal with the Zero. How to find out which ones are raised and which are flush? Good question, wish I could answer it!