Quote - Can it guaranteed that the head folders of all runtimes are called "Runtime"?

Poser: Nope.

D|S: Yep. (it sort of demands it... you select the parent folder of your "Runtime" directory as your D|S Poser content directory. e.g. my A3 runtime directory goes "zzA3Runtime > Runtime > (all the stuff in a typical Runtime directory, etc)"