Up/down, Alcm (auiomaiic irucrcom), Cb (oil back) – NEC 2000IVX User Manual
Page 5: Dicm (dial intercom), Dnd (do not disturb), Fd-a (oil forwarding - all oils), Fd-b (oil forwarding - busy), Fd*n (oil forw'arding - no answer), Fi^-ds (oil forwarding - destination set)