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A MIME Body Part for FAX (RFC2159)

IP.com Disclosure Number: IPCOM000002716D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2019-Feb-15
Document File: 7 page(s) / 9K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

H. Alvestrand: AUTHOR

Related Documents

10.17487/RFC2159: DOI

Abstract

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. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 34% of the total text.

Network Working Group H. Alvestrand Request for Comments: 2159 UNINETT Category: Standards Track January 1998

A MIME Body Part for FAX

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1998). All Rights Reserved.

1. 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.

2. The image/g3fax content-type

This content-type is defined to carry G3 Facsimile byte streams.

In general, a G3Fax image contains 3 pieces of information:

(1) A set of flags indicating the particular coding scheme. CCITT Recommendation T.30 defines how the flags are transmitted over telephones. In this medium, the flags are carried as parameters in the MIME content-type header field.

(2) A structure that divides the bits into pages. CCITT recommendation T.4 describes a "return to command mode" string; this is used here to indicate page breaks.

Alvestrand Standards Track [Page 1]

RFC 2159 MIME Body Part for FAX January 1998

(3) For each page, a sequence of bits that form the encoding of the image. CCITT recommendation T.4 defines the bit image format. This is used without change. The highest bit of the first byte is the first bit of the T.4 bitstream.

2.1. G3Fax Parameters

The following parameters are defined:

(1) page-length - possible values: A4, B4 and Unlimited

(2) page-width - possible values: A3, A4, B4

(3) encoding - possible values: 1-dimensional, 2-dimensional, Uncompressed

(4) resolution - possible values: Fine, Coarse

(5) DCS - a bit string, represented in Base64.

(6) pages - an integer, giving the number of pages in the document

If nothing is specified, the default parameter settings are:

page-length=A4 page-width=A4 encoding=1-dimensional resolution=Coarse

Alvestrand Standards Track [Page 2]

RFC 2159 MIME Body Part for FAX January 1998

It is possible (but misleading) to view the representation of these values as single-bit flags. They correspond to the following bits of the T.30 control string and X.400 G3FacsimileParameters:

Parameter T.30 bit X.400 bit

page-length=A4 no bit set page-length=B4 19 21 page-length=Unlimited 20 20

page-width=A4 no bit set page-width=A3 18 22 page-width=B4 17 23

encoding=1-dimensional no bit set encoding=2-dimensional 16 8 encoding=Uncompressed 26 30

resolution=Coarse no bit se...

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