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WebCGM 2.1 — Introduction to WebCGM
This chapter's sections are informative, unless otherwise
indicated.
This section is normative.
The key words words "MUST", "MUST NOT",
"REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED",
"MAY", and "OPTIONAL" are to be interpreted as
described in [RFC2119].
This section is normative.
- ISO/IEC 8632:1999(E)
- Information technology - Computer graphics - Metafile for the storage
and transfer of picture description information
- Part 1: Functional description
- Part 3: Binary encoding
- Part 4: Clear text encoding
Available at the ISO page of Publicly
Available Standards. CGM:1999 was reaffirmed by ISO, without
changes, at its 5-year review in 2004. The WebCGM profile is defined by
reference to the ISO standard.
- ISO Register
- ISO International
Register of Graphical Items, the normative repository of registered
extensions to ISO CGM. Available at
http://jitc.fhu.disa.mil/nitf/graph_reg/graph_reg.html. An informative summary
of registered CGM items, including pointers into the normative
register, is available at http://www.cgmopen.org/technical/registry/
.
- ISO/IEC 8632-1:1999/Cor 1:2006
- This corrigendum to CGM:1999 corrects an error in the specification
of NURBS knots list in CGM:1999. Available at: http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44114
.
- ISO/IEC 8632-1:1999/Cor
2:2007
- This corrigendum to CGM:1999 clarifies the permissibility and usage
rules of Application Structures in the Text Open State of CGM:1999.
Available at: http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50315
.
- RFC 3986
- Uniform Resource
Identifiers (URI): Generic Syntax, Eds. T.Berners-Lee,
R.Fielding, L.Masinter, January 2005, available at
http://www.ietf.org/rfc/rfc3986.txt .
- RFC 3987
- Internationalized
Resource Identifiers (IRIs), M.Duerst, M. Suignard, January
2005, available at http://www.ietf.org/rfc/rfc3987.txt .
- RFC 1951
- Deutsch, P., "DEFLATE Compressed Data Format Specification version
1.3", RFC1951, Aladdin Enterprises, May 1996. Available at: http://www.ietf.org/rfc/rfc1951.txt
.
- RFC 1952
- Deutsch, P., "GZIP file format specification version 4.3", RFC1952,
Aladdin Enterprises, May 1996, available at: http://www.ietf.org/rfc/rfc1952.txt
.
- ISO/IEC 10646
- ISO (International Organization for Standardization). ISO/IEC
10646-1:2000. Information technology — Universal Multiple-Octet
Coded Character Set (UCS) — Part 1: Architecture and Basic
Multilingual Plane and ISO/IEC 10646-2:2001. Information
technology — Universal Multiple-Octet Coded Character Set (UCS)
— Part 2: Supplementary Planes, as, from time to time,
amended, replaced by a new edition or expanded by the addition of new
parts. [Geneva]: International Organization for Standardization. (See
http://www.iso.ch for the latest version.)
- ISO/IEC 10646-UTF8
- ISO/IEC 10646-1:1993, AM2:1996, Information technology —
Universal multiple-octet coded character set (UCS) — Part 1:
Architecture and Basic Multilingual Plane AMENDMENT 2: UCS
Transformation Format 8 (UTF-8). Available from ISO, see
http://www.iso.ch .
- ITU-jpeg
- Information technology – Digital compression and coding of
continuous-tone still images – Requirements and guidelines.
ITU-T Recommendation T.81. Available at
http://www.w3.org/Graphics/JPEG/itu-t81.pdf. . (ISO/IEC 10918-1 :
1993(E))
- REC-png
- Portable Network Graphics (PNG) Specification (Second Edition) -
Information technology - Computer Graphics and image processing -
Portable Network Graphics (PNG): Functional specification. ISO/IEC
15948:2003(E). W3C Recommendation
10 November 2003, available at
http://www.w3.org/TR/2003/REC-PNG-20031110 .
- RFC 2119
- IETF RFC 2119:
Key words for use in RFCs to Indicate Requirement Levels, S.
Bradner, March 1997. Available at http://www.ietf.org/rfc/rfc2119.txt
.
- XML 1.0
- Extensible
Markup Language (XML) 1.0 (Fifth Edition), Eds. T.Bray,
J.Paoli, C.M.Sperberg-McQueen, E.Maler, F.Yergeau, November 2008,
available at http://www.w3.org/TR/2008/REC-xml-20081126/.
- Namespaces in XML
- Namespaces in XML
1.0 (Second Edition), Eds. T.Bray, D.Hollander, A.Layman,
R.Tobin, August 2006, available at
http://www.w3.org/TR/2006/REC-xml-names-20060816/ .
- RFC 2781
- IETF (Internet Engineering Task Force). RFC 2781: UTF-16, an
encoding of ISO 10646, Eds. P. Hoffman, F. Yergeau.,
February 2000. (Available at http://www.ietf.org/rfc/rfc2781.txt )
- RFC 3629
- UTF-8, a
transformation format of ISO 10646, IETF RFC 3629, STD 63,
Ed. F. Yergeau, November 2003. (See http://www.ietf.org/rfc/rfc3629.txt
)
- Unicode
- The Unicode Consortium, The Unicode Standard, Version 4,
ISBN 0-321-18578-1, as updated from time to time by the publication of
new versions. (See http://www.unicode.org/unicode/standard/versions/
for the latest version and additional information on versions of the
standard and of the Unicode Character Database).
- SVG 1.1
- Scalable Vector Graphics
(SVG) 1.1 Specification, Eds. J.Ferraiolo, J.Fujisawa,
D.Jackson, January 2003, available at http://www.w3.org/TR/SVG11/ .
- DOM Level 3 Core
- Document
Object Model (DOM) Level 3 Core Specification, Eds. A.Le
Hors, P.Le Hégaret (plus L.Wood, G.Nicol, J.Robie, M.Champion,
S.Byrne), April 2004, available at
http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/ .
- DOM Level 3 Events
- Document
Object Model Level 3 Events Specification, Eds. B.Höhrmann,
P.Le Hégaret, T.Pixley, April 2006, available at
http://www.w3.org/TR/2003/NOTE-DOM-Level-3-Events-20031107/ .
- HTML 4.01
- HTML 4.01
Specification, Eds. D.Raggett, A.Le Hors, I.Jacobs, December
1999, available at http://www.w3.org/TR/html401/ .
- CSS 2.0
- Cascading Style Sheets,
level 2, CSS2 Specification, Eds, B.Bos, H.Wium Lie,
C.Lilley, I.Jacobs, May 1998, available at http://www.w3.org/TR/CSS2/
.
- Xpointer Framework
- XPointer
Framework, Eds. P.Grosso, E.Maler, J.Marsh, N.Walsh, March
2003, available at
http://www.w3.org/TR/2003/REC-xptr-framework-20030325/ .
- Cascading Profiles
- Definition and description of how to write a profile using WebCGM as
the starting point, for closely related technical application sectors.
At http://www.cgmopen.org/technical/cascading-profiles.html
.
- WebCGM 2.1
Requirements
- The requirements used to define the new functionality for WebCGM 2.1.
At http://docs.oasis-open.org/webcgm/v2.1/WebCGM_21_Requirements.html.
- WebCGM 2.0
Requirements
- The requirements on which the major WebCGM 2.0 release was based. At
http://www.cgmopen.org/technical/WebCGM_20_Requirements.html
.
- SpecGL 1.0
- The W3C QA
Framework: Specification Guidelines has guided the inclusion
of the normative Conformance clause, and other conformance-related
details of WebCGM. Eds. K.Dubost, L.Rosenthal, D.Hazaël-Massieux,
L.Henderson,August 2005, available at
http://www.w3.org/TR/qaframe-spec/ .
- CGM-MIME
- The IANA registry item for CGM, Final
version of CGM Media Type registration, Alan Francis, 1
November 1995, available at
http://www.iana.org/assignments/media-types/image/cgm .
- StylableCGM
- Stylable
CGM, D.Cruikshank & L.Henderson, a detailed study of
possible relationships between WebCGM and CSS, presented at XML Europe
2003, available at
http://www.cgmopen.org/technical/stylable_cgm_submitted_0324.pdf .
- Unicode TR15
- Unicode Standard
Annex #15, Unicode Normalization Forms, Eds. M.Davis,
M.Dürst, March 2008, available at
http://www.unicode.org/reports/tr15/
- CHARMOD-NORM
- Character Model
for the World Wide Web 1.0: Normalization, Eds. F.Yergeau,
M.Dürst, R.Ishida, A.Phillips, M.Wolf, T.Texin, October 2005, available
at http://www.w3.org/TR/charmod-norm/ .
- UAAG 1.0
- User
Agent Accessibility Guidelines 1.0, Eds. Ian Jacobs, Jon
Gunderson, Eric Hansen, 17 December 2002, a W3C Recommendation
available at
http://www.w3.org/TR/2002/REC-UAAG10-20021217/ .
- WCAG 1.0
- Web
Content Accessibility Guidelines 1.0, Eds. Wendy Chisholm,
Gregg Vanderheiden, Ian Jacobs, 5 May 1999, a W3C Recommendation
available at http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/ .
The scope of this WebCGMTM 2.1 specification includes these
components.
- an intelligent graphics profile of the ISO Computer Graphics Metafile
(CGM) standard (ISO/IEC 8632:1999), tailored to the requirements for
scalable 2D vector graphics in electronic documents on the World Wide
Web;
- a WebCGM Document Object Model (DOM), which provides an application
programming interface to WebCGM objects in WebCGM-supporting
applications;
- definition of a standard WebCGM XML Companion File (XCF), which allows
applications to externalize some non-graphical metadata from WebCGM
instances, yet maintain a tight binding of the metadata to WebCGM
objects.
- definition of an Application Configurable Items (ACI) file, to improve
predictability of interpretation of font specifications, and to
precisesly specify some under-specified defaults.
WebCGM is a set of specifications targeted especially at the effective
application of the ISO CGM:1999 standard to representation of 2D graphical
content within Web documents.
CGM has been an ISO standard since 1987, and CGM has been a registered
media type (image/cgm) for the Internet and the World Wide Web since December
1995. WebCGM
1.0, comprising the original intelligent graphics profile of ISO CGM, was
first published in 1999, was re-released in 2001 with error corrections, and
formed the basis for the significant extensions of the WebCGM
2.0 specification.
For much more information about WebCGM, please see the WebCGM
FAQ, as well as other numerous other references and reading materials, on
the OASIS CGM Open Web site.
The WebCGM profile is a conforming profile of ISO CGM under the
stipulations of CGM:1999 Clause 9, "Profiles and conformance", and it
utilizes the Profile Proforma (PPF) of CGM:1999 Annex I.1, Proforma tables,
for representation of the element-by-element content details.
The WebCGM profile is an "intelligent graphics" profile, which means that
in addition to graphical content based on CGM Versions 1-3, the profile
includes non-graphical content based on CGM Version 4, Application
Structures. The non-graphical content allows the definition of hierarchies of
application objects, as well as the association of metadata, such as link
specifications and layer definitions, with the objects.
The original WebCGM 1.0 profile
resulted from a collaboration between the CGM Open Consortium and W3C
Graphics Activity. The requirements that determined the content selection for
WebCGM 1.0 were derived from:
The selection criteria for the WebCGM profile include:
- graphical content: it should have high expressive power; and, it should
be both widely implemented, and implementable with a reasonable level of
effort.
- intelligence content (structuring and metadata elements): criteria came
from the above-mentioned requirements document, [cgmreq], plus additional
requirements generated during the first 5 years of deployment and use of
the WebCGM 1.0 standard.
The requirements of the major WebCGM
2.0 release -- a set of additions, deletions, and modifications applied
to the 1.0 profile -- were shaped by:
- additional requirements generated during
5 years of deployment of WebCGM 1.0 in industry;
- apparent non-use of certain 1.0 features;
- need for convergence with similar profiles in closely related
industries.
The content of the WebCGM 2.1 profile comprises less than a dozen items
that were arguably within the scope of WebCGM 2.0, but which arose too late
in the standardization of the latter. The WebCGM
2.1 Requirements document summarizes these requirements.
The WebCGM 2.1 intelligent graphics profile, like its predecessors WebCGM
2.0 and WebCGM 1.0, is a profile of the ISO CGM:1999 standard, designed for
effective application of CGM in technical Web applications. WebCGM is not
aimed at or optimized for any particular technical application sector, but is
intended to satisfy general requirements shared by different but closely
related technical Web applications.
Following five years of deployment and application of WebCGM and other
technical profiles (such as Air Transport Association's), some divergence
began to appear. WebCGM 2.0 represented a major effort towards convergence of
intelligent graphics profiles in closely related industries. In fact,
starting with version 2.0, it is the intention of the authors and publishers
of WebCGM that it be used as a basis for the definition of industry-specific
profiles. Cascading
Profiles describes the use of WebCGM as a core profile from which
specific industries derive and define their technical profiles.
CGM:1999 Clause 9, "Profiles and conformance", prescribes that profiles
shall maintain revision control by using a standard "ProfileEd" keyword.
Instances of a profile carry this edition information in their identification
section. Prior releases of WebCGM include:
- WebCGM
Profile, 21 January 1999, the first release of WebCGM
("ProfileEd:1.0").
- WebCGM
1.0 Second Release, 17 December 2001, an errata-correcting
release of the previous (also "ProfileEd:1.0").
- WebCGM 2.0, a
major functional upgrade of WebCGM 1.0, simultaneously published by OASIS
and W3C on 30 January 2007 ("ProfileEd:2.0").
This specification is the first release of WebCGM 2.1 ("ProfileEd:2.1").
There may be future releases of WebCGM 2.1, for maintenance and defect
correction. There may be future higher editions and versions of WebCGM.
A summary of the substantive differences between WebCGM 2.1
and WebCGM 2.0 may be found in the Appendix, "What's new in WebCGM
2.1".
WebCGM is written in these major sections:
- This section, containing introductory and overview material, which is
mostly informative, but does contain two normative
subsections.
- A WebCGM Concepts section,
informative but not normative.
- Detailed descriptive material on the V4
content of WebCGM, including Content Model which can be used for V4
content. This section is normative.
- The definition of a standard XML Companion
File (XCF) for use with WebCGM. This section is
normative.
- The definition of the WebCGM Document
Object Model (DOM). This section is normative (including
normative IDL definitions of the DOM interfaces).
- The Profile Proforma (PPF),
comprising an extensive table which addresses every element of the ISO
CGM standard, per CGM:1999 Annex I. This section is
normative.
- The normative Conformance chapter
describes the conformance targets and conformance details of WebCGM.
- The ECMAScript chapter give a
normative description of an ECMAScript binding for WebCGM DOM.
- The Application Configurable Items
chapter defines an XML format for defaults specification on a number of
WebCGM elements, and for font substitution.
- Appendixes, including informative
sections such as revision history, comparison of WebCGM 2.1 with the
previous version, etc.
Note about CGM examples. In Chapter 5, defining the WebCGM DOM, there are
examples that end with text lines, "View this example as HTML-CGM
(WebCGM-DOM-enabled browsers only.)" In document formats that support
external links (i.e., XHTML), each of these examples links to an XHTML
snippet that invokes WebCGM instances. To view them your browser must have a
WebCGM viewer plug-in, control, or appropriate equivalent technology. To
obtain such a viewer, see for example the (non-exhaustive) CGM products directory
on the OASIS/CGM Open Web site.
Copies of the ISO standards may be obtained from ISO:
ISO Central Secretariat
International Organization for Standardization (ISO)
ch. de la Voie-Creuse
Case postale 56
CH-1211 Geneva 20
Switzerland
For the purpose of this Recommendation and according to the rules for the
designation and operation of registration authorities in the ISO/IEC
Directives, the ISO and IEC Councils have designated the following as the
registration authority:
Joint Interoperability Test Command
ATTN: JTF NITFS Registration Authority (ISO/IEC 9973)
P.O. Box 12798
Fort Huachuca, AZ 85670-2798
USA
For more information on WebCGM and the CGM:1999 standard itself, the CGM
Open Web site has a collection of bibliographic references and short
articles:
- CGM Open
- http://www.cgmopen.org/
These additional World Wide Web sites have more information on CGM:
- W3C WebCGM Overview
- http://www.w3.org/Graphics/WebCGM/
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