Foundation or terminal standard

NEW-ENVIRON

Telnet New Environment Option

In use today Documented current use

Exchanges named environment variables; MNES defines a MUD-oriented set of keys on top of it.

Protocol overview

First seen: 1994
Present-day status: In use today
In use today?: Yes, with documented current use.
Legacy?: No.
Layer: Foundation or terminal standard
Transport: Telnet option 39
Telnet option: 39
Research validated: 2026-08-29

Current use and fit

Implemented by several engines and clients, though MUD-specific use is optional.

Implementation essentials

Only the requesting side asks for variables and only the WILL side sends them.
Escape VAR, VALUE, and ESC control bytes.

Compatibility and safety notes

Environment values are untrusted and must not grant privileges.
Request only values the application needs.

Original specifications and sources

RFC 1572 NEW-ENVIRON Standard

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