What exactly is "Civ2 Multiplayer add-on"?

[cuc]

Mercator's site has two patches for Civilization II Multiplayer, one is the MGE/UCC patch, but the other is "for the Civilization II Multiplayer add-on".

I've always been wondering what the second patch is for, since I've never seen any evidence for the existence of a Civ2 multiplayer add-on. Yet the patch appears genuine.

 

[The_J]

My ultimate classic collection box says "Civ2 + Multiplayer + Conflicts + Fantastic Worlds", so there is for sure one.