TypeR
TypeR(t) = right;
DecrType(TypeR(t)); /* decrement reference count */
ArgR(n) = _makearg(TypeR(t), ap, err);
ArgR(n) = _copyarg(TypeR(t), ArgR(arg), err);
_freearg(TypeR(t), ArgR(arg));
_checkfield(TypeR(t), f, ArgR(arg)));
_checkchar(TypeR(t), c, ArgR(arg)));
_nextchoice(TypeR(t), f, ArgR(arg)));
_prevchoice(TypeR(t), f, ArgR(arg)));