(Original photo has been de-Nazified) I play in 15mm, and I don't use buildings with removable roofs. So, for those times when our little troops have occupied a building, I've made these little markers. I guess they could also be used for concealed deployment.
I intend to number each one on its base, so that if need be I can note on my army list which unit a flag actually refers to. I'll try it with some rub-down lettering I've got lying around, but if need be I can just draw on the numbers with a mapping pen.