https://app.knowbase.one/vault/rfc/docid/1578
RFC1408: Telnet Environment Option
Network Working Group D. Borman, Editor Request for Comments: 1408 Cray Research, Inc. January 1993 Telnet Environment Option Status of this Memo ...
https://app.knowbase.one/vault/rfc/docid/5652
RFC5183: Sieve Email Filtering: Environment Extension
Network Working Group N. Freed Request for Comments: 5183 Sun Microsystems Category: Standards Track May 2008 Sieve Email Filtering: Environment Extension Status of Thi...