I'm familiar with the 4e guide terminology for A and V classes: A classes have one primary stat and two secondaries you can choose between, with the choice determining the way the class plays; V classes have a choice of two primary stats to determine how the class plays, but the secondary stat remains the same.
But I've run across a few references to E classes (in various rescues of class handbooks and the comments associated with them, like this one or this one), the meaning of which I can't quite infer from context.
In 4e guide vocabulary, what is an "E class"?