I’ve gone ahead and created the MCCP3 standard, primarily for my own purposes, but I figured others might find it of use. MCCP2 compresses data send from the server to the client. MCCP3 compresses data send from the client to the server.
MCCP 1 uses TELNET option 85.
MCCP 2 uses TELNET option 86.
MCCP 3 uses TELNET option 87.
MCCP1 is obsolete. MCCP2 and MCCP3 are described at this page:
Client side MCCP3 support is enabled in TinTin++ 2.01.8
Server side MCCP3 support has been added to my MTH telnet snippet, which will also run stand alone in case client developers need a server to test on.
For the typical MUD server MCCP3 will not result in a large bandwidth reduction as is the case with MCCP2, but MCCP3 will add a little bit of security through obscurity by no longer sending passwords and commands as plain text.