Ancillary or client protocol

MPLEX

Multi-screen Telnet Extension

Historical Not in common current use Legacy

Creates multiple terminal screen contexts that can be selected, shown, hidden, and resized.

Protocol overview

First seen: Circa 2002
Present-day status: Historical
In use today?: No common current use was verified.
Legacy?: Yes. It may still matter for compatibility or historical systems.
Layer: Ancillary or client protocol
Transport: Non-standard Telnet option 112
Telnet option: 112
Research validated: 2026-08-29

Current use and fit

Only a narrow Cryosphere and Crystal history is documented; no broad contemporary adoption was verified.

Implementation essentials

Maintain independent ANSI parser state for every screen.
Implement only for a named compatibility target.

Compatibility and safety notes

The option number is not an IANA assignment.
Contemporary client support is extremely limited.

Original specifications and sources

MUD Standards preservation Preservation

Where an original site has disappeared, a preservation archive is linked and identified as such. MUDVerse does not claim authorship of the original protocol.