Bluefin naming: "handle" or "capability"?

I quite like capability when referring to the effect system members and handles when talking about the what the function requires to provide the effect.

Reading the type signature for fooBf, I read it as:

"fooBf is a computation in which capability e is a member of the capabilities es and it takes a handle to an IOE effects over capability e which it will use to produce an Effect and a return value from the es effect sytem of type r.”

EDIT: IOE e and fooBF does not use other effects in es. The effect is locked to whatever IOE effects e can effect in es.