While CXR is available to anyone, I think, I believe it is still a mostly regional rating system (OK, AR, KS, maybe some MO and TX?), but one that is growing.
There is a -- option that could be used, since there isn't a specific one. I haven't tried switching my flag to see if any other ones show up but at least with the US flag they don't have ECF listed (I think they just have National for that).
edit: nevermind, the -- just deletes anything there.
Hey, so my club has been using Chess eXpress Ratings (CXR) for about a year. It's an alternative to USCF, with a different membership model in order to lower costs for new or infrequent players. I see in the profile section you can choose between several ratings orgs, like FIDE or USCF. Would chess.com be willing to add CXR as an option?