Browse Prior Art Database

UTF-8, a transformation format of ISO 10646 (RFC2279)

IP.com Disclosure Number: IPCOM000002840D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2019-Feb-15
Document File: 10 page(s) / 14K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

F. Yergeau: AUTHOR

Related Documents

10.17487/RFC2279: DOI

Abstract

UTF-8, the object of this memo, has the characteristic of preserving the full US-ASCII range, providing compatibility with file systems, parsers and other software that rely on US-ASCII values but are transparent to other values. This memo updates and replaces RFC 2044, in particular addressing the question of versions of the relevant standards. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 16% of the total text.

Network Working Group F. Yergeau Request for Comments: 2279 Alis Technologies Obsoletes: 2044 January 1998 Category: Standards Track

UTF-8, a transformation format of ISO 10646

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.

Abstract

ISO/IEC 10646-1 defines a multi-octet character set called the Universal Character Set (UCS) which encompasses most of the world’s writing systems. Multi-octet characters, however, are not compatible with many current applications and protocols, and this has led to the development of a few so-called UCS transformation formats (UTF), each with different characteristics. UTF-8, the object of this memo, has the characteristic of preserving the full US-ASCII range, providing compatibility with file systems, parsers and other software that rely on US-ASCII values but are transparent to other values. This memo updates and replaces RFC 2044, in particular addressing the question of versions of the relevant standards.

1. Introduction

ISO/IEC 10646-1 [ISO-10646] defines a multi-octet character set called the Universal Character Set (UCS), which encompasses most of the world’s writing systems. Two multi-octet encodings are defined, a four-octet per character encoding called UCS-4 and a two-octet per character encoding called UCS-2, able to address only the first 64K characters of the UCS (the Basic Multilingual Plane, BMP), outside of which there are currently no assignments.

It is noteworthy that the same set of characters is defined by the Unicode standard [UNICODE], which further defines additional character properties and other application details of great interest to implementors, but does not have the UCS-4 encoding. Up to the

Yergeau Standards Track [Page 1]

RFC 2279 UTF-8 January 1998

present time, changes in Unicode and amendments to ISO/IEC 10646 have tracked each other, so that the character repertoires and code point assignments have remained in sync. The relevant standardization committees have committed to maintain this very useful synchronism.

The UCS-2 and UCS-4 encodings, however, are hard to use in many current applications and protocols that assume 8 or even 7 bit characters. Even newer systems able to deal with 16 bit characters cannot process UCS-4 data. This situation has led to the development of so-called UCS transformation formats (UTF), each with different characteristics.

UTF-1 has only historical interest, having been removed from ISO/IEC 10646. UTF-7 has the quality of encoding the full BMP repertoire using only octets with the high-order bit clear (7 bit US-ASCII values, [US-ASCII]), and is thus deemed a mail-sa...

Processing...
Loading...