STANDARDS for CGM
Standards - ISO 8632; ANSI;
Amendments - CGM Amendment 1; CGM
Profiles - Model profile; ATA;
It all starts with ISO 8632:1992, a.k.a CGM:1992. In a nutshell:
The International Standard - ISO 8632:1992 consists
of 4 parts and 2 amendments.
ISO/IEC 8632.1:1992 ---- Part 1: Functional specification
ISO/IEC 8632.2:1992 ---- Part 2: Character encoding
ISO/IEC 8632.3:1992 ---- Part 3: Binary encoding
ISO/IEC 8632.4:1992 ---- Part 4: Clear text encoding
ISO/IEC 8632:1992/Amd.1: - Amendment 1: Rules
for profiles (parts 1-4)
ISO/IEC 8632:1992/Amd.2 - Amendment 2: Application
structuring extensions (parts 1-4)
Note: The designation ISO 8632:1992 is equivalent to ISO 8632.1-4:1992.
The '.1-4' is used to indicate the part number.
The ANSI Standard - ANSI/ISO 8632.1-4:1992 adopts
CGM:1992. (There is no difference)
The FIPS (Federal Information Processing Standard)
- adopts ANSI/ISO 8632:1992 and several application profiles. NOTE: This
FIPS has been withdrawal from the FIPS series (announced
in the Federal Register February 24, 1998)
Application profiles (AP) are subsets of CGM:1992,
defined by application communities to promote interoperability among users
of the AP. There are several CGM APs:
ISO 8632:1992 is a graphics data interchange standard which defines a neutral
computer interpretable representation of 2D graphical (pictorial) information
in a manner that is independent from any particular application or system.
The purpose of the standard is to facilitate the storage and retrieval
of graphical information between applications, software systems, and/or
devices. A CGM can contain:
The CGM standard defines 3 upward compatible versions. Version 1 provides
a basic drawing and picture interchange capability. The Version 1 metafile
definition includes about 90 elements (i.e., individual function or entity).
Version 1 metafiles are essentially the same as the 'old standard', CGM:1987
(see History). The Version 2 metafile definition contain
approximately 30 additional elements. (All Version 1 metafile elements
are allowed in Version 2 metafiles). The most significant new capability
of Version 2, is the graphical segment. A segment is a group of primitives
that is saved once and named, and then may be used repeatedly in the metafile.
Version 3 metafiles represent a major increase in graphical expressive
power. Version 3 metafiles contain about 40 new elements above the Version
2 capabilities. Version 3 metafile functionality includes: the capability
to represent compressed tiled images, define external symbol libraries,
and greater control of drawing aspects for graphics arts, presentation
graphics, and electronic publishing.
vector graphics (e.g., polylines, ellipses, NURBS),
raster graphics (e.g., tile array), and
Amendments to CGM:1992.
Amendment 1, Rules for Profiles specifies how
profiles should be written. Although it adds no new functionality, it provides:
The PPF (profile proforma) is a set of tables which is a template for writing
profiles. CGM Amendment 1 requires that all profiles shall include a completed
rules for writing profiles,
definition of conforming generators, interpreters, and metafiles, in terms
of profiles, and
a Model Profile - a usable, implementable profile of CGM. Also can be used
as a guide (example) to writing profiles.
ATTENTION PROFILE WRITERS --- It is recommended that the PPF tables
be used in conjuction with the Model Profile to write profiles. Use the
Model Profile as a starting point from which an application specific profile
should be defined. Consider each of the specifications of the Model Profile
and either accept the specifications where they are adequate, or modify
them when not.
Amendment 2, Application Structuring Extensions
addresses the functional requirement for access to arbitrarily small pieces
of the metafile or picture. Application areas targeted for this 'intelligent
graphics' capability include: electronic review of documents, graphical
object databases, network distributed graphical applications, and multi-media
and hyper-media documents.
History - The CGM standard was originally
published in 1986 by ANSI as X3.122-1986. The same standard was published
a year later by ISO as ISO 8632:1987. To make it easier to manage changes,
ANSI X3.122:1986 was replaced by ANSI/ISO 8632:1987 in 1991. There were
3 amendments to CGM:1987, two of which are incorporated in the new, republished
CGM:1992. The other amendment and CGM:1987 were canceled.
The ANSI CGM standard is identical to ISO 8632. The '' in ANSI/ISO
8632:1992 refers to the year that ANSI officially adopted CGM:1992.
The previous ANSI CGM standard, X3.122:1986 is obsolete - throw it out!
do not use it!
The Federal Register, February 24, 1998 announced the proposed withdrawal
of FIPS 128-2 from the FIPS series. FIPS 128-2 is being withdrawn because
it adopted voluntary standards (ISO 8632, ATA and CALS profiles) and had
not been updated to reference current or revised voluntary industry standards.
An application profile (AP) defines the options, elements, and parameters
of ISO 8632 necessary to accomplish a particular function and maximize
the probability of interchange between systems implementing the profile.
Profiles are defined by application constituencies who agree to adhere
to the same subset of CGM for the purpose of graphical data interchange
using ISO 8632. A profile addresses metafile requirements as well as generator
and interpreter implementation requirements.
There are several prominent profiles:
The Model Profile is defined in CGM:1992.
It is a general purpose profile which supports all 3 CGM encodings at the
CGM Version 3 functionality level. It is appropriate for basic scientific
and technical graphics (e.g., computer-aided design, mapping, earth sciences,
cartography) and presentation, visualization, and publishing applications.
Profile, ATA Specification 2100, GREXCHANGE has been developed
for technical documentation of the manufacture and operation of commercial
airplanes. The profile supports the binary and clear text encodings at
the CGM Version 3 functionality level. It is appropriate for the exchange
of technical manuals, publishing applications, and visualization. A second
profile, ATA Specification 2100, IGEXCHANGE provides for the transfer of
intelligence associated with grahpical data. This profiles supports
the application structuring defined in CGM Amendment 2.
Both profiles are developed and maintained by the ATA/AIA (Airline
Transport Assoc. and Airline Industry Assoc.). Information about this profile
can be obtained from ATA at 1301 Pennsylvania Ave. N.W., Suite 1100, Washington,
D.C. 10004-1707, (202)626-4000
profile is a W3C Recommendation. It was developed by members
of W3C and CGM experts. The goal is to develop an effective profile for
use of CGM in Web applications.
profile, MIL-D-28003A, was developed by the U.S. Department of
Defense for technical illustrations and publications. The profile supports
the binary encoding at the CGM Version 3 functionality level. There are
many implementations that support this profile at the CGM Version 1 level.
This profile does not follow the rules of CGM Amendment 1, since it was
produced prior to Amendment 1.
profile has been developed for graphical interchange between petrotechnical
applications in the petroleum exploration and production community. For
more information about this profile, contact: Petrotechnical Open Software
Corporation, Graphics Metafile Format RFC, 10777 Westheimer, Suite 275,
Houston, TX 77042, (713)784-9219