Rabbit Genetics Ed and "chin medium"?

[SJRabbitryandfarm]

so reading up on genetics and this gene Ed keeps popping up . but i have never ever seen it talked about in any genetics groups or in most color groups. does anyone have extra info on it ..? is Ed probably just EsEs ? or are they entirely different . another one is Chin medium... anyone have any info about that one? is it more likely just modifiers you see on chin genes ??
can find Ed talked about on osu's website . and I cant find the page I read about chin medium on any more .. ?