IETF RFC 2159 PDF

Introduction

This document contains the definitions, originally contained in RFC 1494, on how to carry CCITT G3Fax in MIME, and how to translate it to its X.400 representation.

NOTE: At the moment, this format does not seem appropriate for a "general purpose image format for the Internet", if such a beast can exist. It exists only to carry information that is already in G3 Fax format, and may be usefully converted to other formats when used in specific contexts.