The more elegant bracket notation [Z?B] is ambiguous, because it is not clear what 'forward' is for a diagonal step after a Z leap.
Afterthought: I'd think of "forward" from a hippogonal move as being parallel to the nearest orthogonal line (or, for a diagonal move, the nearest diagonal line).
Afterthought: I'd think of "forward" from a hippogonal move as being parallel to the nearest orthogonal line (or, for a diagonal move, the nearest diagonal line).