For historical amusement... In reading the Phase II NSP spec, I spotted a summary of how that differs from Phase I. I've never seen any Phase I documents (perhaps no formal documents ever existed?). From the discussion in the Phase II spec, it's clear that Phase I is quite a different protocol. Phase II through IV are all very closely related, especially at layer 4 and above. Not so Phase I -- it would be quite difficult (at best) to make an NSP implementation that could speak both Phase I and Phase II. I don't see any signs that this was ever done. For example, there is no "how to interoperate with the previous version" chapter in the Phase II spec -- unlike the Phase III and IV specs. paul