http://www.rfc-editor.org/rfc/rfc4616.txt
RFC 4616: The PLAIN Simple Authentication and Security Layer (SASL) Mechanism, K. Zeilenga2006-08-01T23:00:00-00:00This document defines a simple clear-text user/password Simple Authentication and Security Layer (SASL) mechanism called the PLAIN mechanism. The PLAIN mechanism is intended to be used, in combination with data confidentiality services provided by a lower layer, in protocols that lack a simple password authentication command. [STANDARDS-TRACK]