Here's a couple showing stand seam tabs. Flat seamed is similar but IIRC the tab may be folded over the nail head.
from Old House Journal 1994 when it still had a 'how things are done' focus.
Yeah, but you are talking about a flat tin roof laid over a surface and seamed. Stamped steel roofs are totally different. They use screw attachments and the sections overlay each other kinda like a shingle roof using nails.