http://www.rfc-editor.org/rfc/rfc4289.txt
RFC 4289: Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures, N. Freed, J. Klensin2005-12-01T23:00:00-00:00This document specifies IANA registration procedures for MIME external body access types and content-transfer-encodings. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.