Browse Prior Art Database

A MIME Body Part for FAX (RFC2159)

IP.com Disclosure Number: IPCOM000002716D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 5 page(s) / 10K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

H. Alvestrand: AUTHOR

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.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 29% 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.

(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

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 bi...