Our goal is to make our modules compatible with modules from the many other Free-Mo groups around North America. In order to meet this goal the New England Free-mo Group constructs their modules in accordance with the North American Free-mo standard.
While there’s not an “official” governing body overseeing the standard much of the discussion and consensus regarding standards takes place in a Yahoo Free-mo discussion group.
There is also a Draft Standards & Recommended Practices that helps clarify things a bit.
Also there’s a Gentle Guide to the Free-mo Standards that has some helpful guidance.