D. Connolly
Internet-Draft World Wide Web Consortium (W3C)
L. Masinter
Xerox Corporation
September 21, 1999
draft-connolly-text-html-00.txt
Obsoletes: RFC 1866, RFC 2070, RFC 1980, RFC 1867, RFC 1942
The 'text/html' Media Type
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026.
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
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Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
Abstract
This document summarizes the history of HTML development, and
defines the "text/html" MIME type by pointing to the relevant W3C
recommendations, It is intended to obsolete the previous IETF
documents defining HTML, including RFC 1866, RFC 1867, RFC 1980,
RFC 1942 and RFC 2070.
This document was prepared at the request of the W3C HTML working
group. Please send comments to www-html@w3.org, a public mailing
list with archive at
<http://lists.w3.org/Archives/Public/www-html/>.
1. Introduction and background
The text/html media type was originally defined in [HTML20] in Nov
1995. Extensions to HTML were proposed in [HTML30], [UPLOAD],
[TABLES], [CLIMAPS], and [I18N].
The IETF HTML working group closed Sep 1996, and work on HTML moved
to the World Wide Web Consortium (W3C). The proposed extensions
were incorporated, to some extent, in [HTML32], and to a larger
extent, in [HTML40]. The definition of multipart/form-data from
[UPLOAD] was described in [FORMDATA]. In addition, a reformulation
of HTML 4.0 in XML 1.0 is being developed [XHTML1].
[HTML32] notes "This specification defines HTML version 3.2. HTML
3.2 aims to capture recommended practice as of early '96 and as
such to be used as a replacement for HTML 2.0 (RFC 1866)."
Subsequent specifications for HTML describe the differences
in each version.
2. Definition for 'text/html'
The 'text/html' media type is now defined by W3C recommendations;
the latest published version is [HTML40]. As of this writing, a
revision, HTML 4.01 [HTML401], is being developed. In both [HTML40]
and [HTML401].
The "text/html" media type may be used to refer to any W3C
published version of HTML; the versions are distinguishable by the
"DOCTYPE" declaration contained within them. In addition, [XHTML1]
defines an profile of use of XHTML which is compatible with HTML
4.0, and which may also be served as 'text/html'.
MIME media type name: text
MIME subtype name: html
Required parameters: none
Optional parameters: charset
The optional parameter "charset" refers to the character encoding
used to represent the HTML document as a sequence of bytes. Any
registered IANA charset may be used, but UTF-8 is preferred.
Although this parameter is optional, it is recommended that it
always be present.
Encoding considerations:
Because of the availability within HTML itself for using
character entity references for non-ASCII characters, it is
possible that text/html documents with a wide repertoire may be
transported without encoding. Otherwise, transport of text/html
using charsets other than US-ASCII may require base64 or
quoted-printable encoding for 7-bit channels.
Security considerations:
See section 3 of this document.
Additional information:
Magic number:
There is no single initial string that is always present for
HTML files.
Almost all HTML files have the string "<html" or "<HTML" near
the beginning of the file.
Documents conformant to HTML 2.0, HTML 3.2 and HTML 4.0 will
start with a DOCTYPE declaration "<!DOCTYPE HTML" near the
beginning, before the "<html". These dialects are case
insensitive. Files may start with white space, comments
(introduced by "<!--" ), or processing instructions (introduced
by "<?") prior to the DOCTYPE declaration.
XHTML documents (optionally) start with an XML declaration
which begins with "<?xml" and are required to have a DOCTYPE
declaration "<!DOCTYPE html".
File extension:
The file extensions 'htm' or 'html' are commonly used, but
other extensions denoting file formats for preprocessing are
also common.
Macintosh File Type code: HTML
3. Security Considerations
[HTML40], section B.10, notes various security issues with
interpreting anchors and forms in HTML documents.
In addition, the introduction of scripting languages and
interactive capabilities in HTML 4.0 introduced a number of
security risks associated with the automatic execution of programs
written by the sender but interpreted by the recipient. User
agents executing such scripts or programs must be extremely careful
to insure that untrusted software is executed in a protected
environment.
4. Author's Address
Daniel W. Connolly
World Wide Web Consortum (W3C)
MIT Laboratory for Computer Science
545 Technology Square
Cambridge, MA 02139, U.S.A.
phone:+1-512-310-2971
mailto:connolly@w3.org
http://www.w3.org/People/Connolly/
Larry Masinter
Palo Alto Research Center
Xerox Corporation
3333 Coyote Hill Road
Palo Alto, CA 94304
mailto: masinter@parc.xerox.com
http://purl.org/NET/masinter
4. References
[HTML30] "HyperText Markup Language Specification Version 3.0." Dave
Raggett, September 1995. Internet Draft (expired). Available
at <http://www.w3.org/MarkUp/html3/CoverPage>.
[HTML20] "Hypertext Markup Language - 2.0." T. Berners-Lee &
D. Connolly. RFC 1866. November 1995. Additional information
available at <http://www.w3.org/MarkUp/html-spec/>.
[UPLOAD] "Form-based File Upload in HTML." E. Nebel & L. Masinter. RFC
1867. November 1995.
[TABLES] "HTML Tables." D. Raggett. RFC 1942. May 1996.
[CLIMAPS] "A Proposed Extension to HTML : Client-Side Image Maps."
J. Seidman. RFC 1980. August 1996.
[HTML32] "HTML 3.2 Reference Specification." Dave Raggett. W3C
Recomendation. 14 January 1997. Available at
<http://www.w3.org/TR/REC-html32>.
[I18N] "Internationalization of the Hypertext Markup Language." RFC
2070. F. Yergeau, G. Nicol, G. Adams, M. Duerst. January
1997.
[FORMDATA] "Returning Values from Forms: multipart/form-data". RFC
2388. L. Masinter. August 1998.
[HTML40] "HTML 4.0 Specification." Raggett, Le Hors, Jacobs. W3C
Recommendation. 18 Dec 1997. Available at
<http://www.w3.org/TR/REC-html40>.
[HTML401] "HTML 4.01 Specification." D. Raggett, A. Le Hors,
I. Jacobs. W3C Proposed Recommendation (work in progress),
August 1999. Available at
<http://www.w3.org/TR/1999/PR-html40-19990824>.
[XHTML1] "XHTML 1.0: The Extensible HyperText Markup Language: A
Reformulation of HTML 4.0 in XML 1.0." W3C HTML Working
Group. W3C Proposed Recommendation (work in progress). August
1999. Available at <http://www.w3.org/TR/xhtml1>.