ISO/IEC 9636-1:1991

Information technology - Computer graphics - Interfacing techniques for dialogues with graphical devices (CGI) - Functional specification - Part 1: Overview, profiles, and conformance

Includes a reference model, the relationship to other standards, and profiles. Establishes the framework for all the parts of ISO/IEC 9636. Does not contain functional descriptions.

Technologies de l'information — Infographie — Interfaces pour l'infographie — Spécifications fonctionnelles — Partie 1: Résumé, profils et conformité

General Information

• Status: Published
• Publication Date: 17-Dec-1991
• ICS: 35.140 - Computer graphics
• Technical Committee: ISO/IEC JTC 1/SC 24 - Computer graphics, image processing and environmental data representation
• Drafting Committee: ISO/IEC JTC 1/SC 24/WG 6 - Computer Graphics and Virtual Reality
• Current Stage: 9093 - International Standard confirmed
• Start Date: 08-Dec-2021
• Completion Date: 30-Oct-2025

Relations

• Child: ISO 23748:2016 - Aerospace series - O-ring grooves - Dimensions
• Effective Date: 06-Jun-2022

Overview

ISO/IEC 9636-1:1991 - "Information technology - Computer graphics - Interfacing techniques for dialogues with graphical devices (CGI) - Functional specification - Part 1: Overview, profiles, and conformance" defines the framework for the Computer Graphics Interface (CGI). Part 1 provides the reference model, the relationship to related standards, and a profile/conformance framework for all parts of ISO/IEC 9636. It does not contain the per-function functional descriptions - those appear in Parts 2–6 - but establishes the architecture, terminology and requirements implementers must follow.

Key topics and technical requirements

• Reference model and client/target relationships: Describes CGI configurations and example setups (virtual devices, input/output workstations) to standardize device-independent vs device-dependent roles.
• Profiles and profile registration: Defines Foundation Profiles and Constituency Profiles (e.g., GKS and CGM constituency profiles), and provides formats and identifiers for classifying implementations.
• Conformance and classification: Rules for implementation conformance, client conformance, allowed extensions, parsing, and inquiry behaviour.
• Global CGI concepts: Coverage of the CGI graphic object pipeline, state model, description tables and state lists, static vs dynamic state, inquiry principles, and error philosophy.
• Data and grammar guidance: Document outlines data types, formal grammar, and guidelines for bindings and encodings without mandating a protocol - enabling software-to-software or software-to-hardware interfaces and network encodings.
• Annexes and guidance: Informative annexes include bindings/encodings guidelines, profile format templates, and distributed system considerations.

Practical applications and users

ISO/IEC 9636-1 is aimed at enabling device-independent graphics interoperability and portability. Practical uses include:

• Designing graphics system architectures and CGI-compliant device drivers so new devices plug into existing software without code rewrites.
• Defining data stream encodings and procedural language bindings for networked graphics or device protocols.
• Establishing conformance test criteria for vendors and integrators to certify compatibility with CGI profiles.
• Academic and training programs teaching standardized graphics APIs and methodologies.

Primary users:

• Graphics system architects and software developers
• Device and driver vendors
• Standards bodies and test labs
• Integrators building distributed or networked graphics systems

Related standards

ISO/IEC 9636-1 situates CGI relative to other standards and parts:

• ISO/IEC 9636 Parts 2–6 (Control, Output, Segments, Input and echoing, Raster)
• Graphics standards such as GKS, GKS-3D, PHIGS, and CGM
• Standards for data encodings and language bindings referenced in annex guidance

Keywords: ISO/IEC 9636-1, Computer Graphics Interface (CGI), computer graphics standard, device-independent graphics, graphics interface profiles, conformance, GKS, CGM, PHIGS, data encodings, language bindings.

Standards Content (Sample)

ISOIIEC
INTERNATIONAL
STANDARD 9636-1
First edition
1991-12-15
Information technology - Computer graphics -
Interfacing techniques for dialogues with
graphical devices (CGI) - Functional
specification -
Part II:
Overview, profiles, and conformance
Technologies de /‘information -- Infographie - Interfaces pour
I’infographie - Sp&ifkations fonctionnelles -
Partie 1: R&um& profils et conformitt?
Reference number
lSO/IEC 96364:1991(E)
ISO/IEC 9636-l : 1991 (E)
Page
Contents
iV
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.~.
V
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.
1 .
scope
........................................................................
1.1 Relationship of CGI to a computing environment
.................................................................................. 2
1.2 Position of CGI in a managed environment
Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.*.*.
Definitions and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.
3.1 Organization of the defmitions . . . . . . . . . . . . . . . .*.
3.2 Definitions .,. l . . . . . . . . .
3.3 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.“.~.
4 Reference models .
4.1 Introduction .
...................................................................................... 18
4.2 Model for CGI client/target relationships
4.2.1 CGI configurations diagram .
Types of clients .
4.2.2
Types of targets .
4.2.3
.................................................................................................................
4.3 Example configurations
................................................................. 21
4.3.1 CGI Virtual Devices as GKS workstations
....................................................................................
4.3.2 CGM interpretation using CGI
CGI Virtual Devices as 3D workstations .
4.33
.......................... 22
Input/output workstations as combinations of CGI Virtual Devices
4.3.4
.....................................................................................................
4.4 Relationship to other standards
.................................................................................................................
4.4.1 Introduction
..................................................................................... 24
4.4.2 CGI data encodings standards
................................................................................
4.43 CGI language bindings standards
..............................................................................
4.4.4 Relation to GKS (IS0 7942 1985)
1989) and PHIGS (ISO/I[EC 9592 1989). .
4.45 Relation to GKS-3D (IS0 8805
.............................................................................
4.4.6 Relation to CGM (IS0 8632 1987)
4.4.7 Relation to Procedures for Registration of Graphical Items
(ISO/IEC TR 9973 1988) .
5 Concepts .
....................................................................................................................................
5.1 Introduction
.....................................................................................................................
5.2 Global CGI concepts
......................................................................................
5.2.1 CGI Graphic Object Pipeline
...........................................................................................................
5.2.2 CGI state model
........................................................................................................
5.2.3 Description tables
5.2.4 State lists .
5.2.5 Static and dynamic state lists .
........................................................ 33
5.2.6 The structure of description tables and state lists
The principles of inquiry .
5.2.7
..........................................................................................................
5.2.8 Error philosophy
Method of describing functions .
5.2.9
...................................................................................................
5.2.10 Data types employed
.......................................................................................................... 39
5.2.11 Formal grammar
........................................................................................ 40
53 Overview of ISO/IEC 9636-2 : Control
5.4 Overview of ISO/IEC 9636-3 : Output .
5.5 Overview of ISO/IEC 9636-4 : Segments .
5.6 Overview of ISO/IEC 9636-5 : Input and echoing .
.......................................................................................... 41
5.7 Overview of ISO/IEC 9636-6 : Raster
0 ISO/IEC 1991
All rights reserved. No part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission
in writing from the publisher.
ISO/IEC Copyright Office l Case postale 56 l CH-1211 Geneve 20 a Switzerland
Printed in Switzerland
ii
ISO/IEC 9636-l : 1991 (E)
6 Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1 Profile defmi tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Constituency Profile registration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 43
6.1.1
6.2 Foundation Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3 Constituency Profiles .
6.3.1 GKS Constituency Profiles .
6.3.2 CGM Constituency Profile .
.......................................................... 44
6.3.3 Advanced l-Way Output Constituency Profile
........................................................................................................ 44
6.4 Foundation Profile definition
........................................................................ 44
6.4.1 2-WAY OUTPUT Foundation Profile
1 -WAY OUTPUT Foundation Profile . 45
6.4.2
INPUT Foundation Profile . 46
6.4.3
.................................................................................................................. 46
6.5 GKS Profile definition
............................................................................................ 46
65.1 GKS OUTPUT-O Profde
............................................................................................ 49
6.5.2 GKS OUTPUT-l Profile
6.53 GKS INPUT-b Profile .
.......................................................................... 53
65.4 GKS INPUT-c Profile
65.5 GKS OUTIN-Ob Profile .
.............................................................................................. 54
65.6 GKS OUTIN-Oc Profile
65.7 GKS OUTIN-lb Profile .
65.8 GKS OUTIN-lc Profile .
6.6 CGM Profile definition . 55
6.6.1 BASIC CGM Profile . 55
6.7 Other Constituency Profile definitions .
6.7.1 ADVANCED l-WAY OUTPUT Profile .
7 Classification and designation . 59
7.1 Implementation conformance . 59
7.2 Client conformance .
7.3 Extensions .
7.4 Inquiry .
7.5 Parsing .
A Function identifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
B Profile identifiers . . . . . . . . . . . . . .*. 69
C Guidelines for bindings and encodings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
D Format guidelines for definition of Constituency Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
E CGI in a distributed system model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
F Typographic conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
. . .
ill
ISO/IEC 9636-l : 1991 (E)
Foreword
IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the
development of International Standards through technical committees established by the respective organization to deal with
particular fields of technical activity. IS0 and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with IS0 and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft
International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
International Standard ISO/IEC 9636-l was prepared by Joint Technical Committee ISODJX JTC I, Information
technology.
ISO/IEC 9636 consists of the following parts, under the general title Information technology - Computer graphics -
Intevacing techniques for dialogues with graphical devices (CGI) - Functional specification:
- Part 1: Overview, profiles, and conformance
-Part 2: Control
-Part 3: Output
-Part 4: Segments
-Part 5: Input and echoing
- Part 6: Raster
Annexes A and B form an integral part of this part of ISO/IEC 9636. Annexes C, D, E and F are for information only.

ISO/IEC 9636-l : 1991 (E)
Introduction
Purpose
The Computer Graphics Interface (CGI) specifies a standard interface between device-independent and device-dependent parts
of a graphics system. ISO/IEC 9636 specifies sets of functions for control and data exchange over this interface. This interface
may be implemented as a software-to-software interface (as a data stream encoding used in a network environment or as a
procedural binding to one or more software packages), or as a software-to-hardware interface (as a data stream encoding to
one or more devices presenting a standardized Computer Graphics Interface as their device protocol). Related standards
specify data stream encodings (for use in the software-to-software case, over a network, and in the software-to-hardware case),
and procedural bindings (for use in the software to software case).
ISO/IEC 9636 includes a reference model and a description of the CGI’s relationship to other standards.
ISO/IEC 9636 only defines graphics functions, graphics control functions, and functions to control data representations and
deferral in data stream encodings. ISO/IEC 9636 does not define the protocols to be used to convey these functions between
the parts of a (potentially distributed) system.
Benefits
Intrinsic The CGI will simplify the development and implementation of graphics systems. ISO/IEC 9636 will encourage
a uniform access to the graphics devices within an installation. As new devices are made available, graphics
device drivers adhering to this interface can be installed for use by existing programs.
Interchange ISO/IEC 9636 promotes the exchange of software between installations. By isolating the device-dependent
aspects of any graphics system, modularity is encouraged, which promotes increased portability. The standard
set of functions, access mechanisms, and terminology will allow developers and users to move between
installations with minimal retraining.
Educational The standard set of functions uses a standard terminology. This allows both the academic and industrial
communities to develop instructional programs concentrating on programming techniques and methodologies
based on these standard functions.
Economic In view of the trend towards lower hardware and higher software costs, the following benefits accrue from
ISO/IEC 9636:
-
It encourages transporting of software between installations, thereby reducing costs associated with
“reinvention”;
-
It protects the large software investment made by both users and vendors because the software will not be
rendered obsolete by the introduction of new devices;
-
It allows developers of new software to focus on higher-level graphics functions and applications instead of
device-level functions;
-
It reduces maintenance of software systems because the standard encourages modularity;
-
It increases vendor independence for the user because any system designed to use a particular device can
more easily be changed to use some other device;
-
It allows vendors to develop and market devices that will easily interface to the customer’s system;
-
It enables users, manufacturers and vendors to take advantage of new, lower-cost graphics hardware
designs. The total system’s hardware cost may be reduced because system redesign may not be necessary.

ISO/IEC 9636-l : 1991 (E)
Design requirements
To realize the benefits described above, a number of design principles have been adopted:
The Computer Graphics Interface should provide a suitable set of functions for the description of a wide range of
pictorial information;
The Computer Graphics Interface should provide a suitable set of functions for the necessary CGI session control of a
wide range of graphics devices;
The Computer Graphics Interface should address the more usual and essential features found on graphical devices
directly and should provide access to less common facilities;
The design of the Computer Graphics Interface should not preclude extension of ISO/IEC 9636 at a later stage to
cover facilities currently not standardized;
The Computer Graphics Interface should be usable from GKS (Graphical Kernel System - IS0 7942). In particular,
the CGI should include functional capability to support the various levels of a GKS workstation in an efficient and
concise manner, without compromising the ability of the interface to support non-GKS systems in an efficient and
concise manner;
The Computer Graphics Interface should be compatible with the Computer Graphics Metafile - IS0 8632. In
particular, those CGM elements not associated with the file-oriented aspects of the CGM shall have corresponding
CGI functions which have identical abstract names and parameterization;
ISO/IEC 9636 should address the needs of different applications that have conflicting requirements for
- allocation of processing burden between host and device;
-
speed of generation and interpretation of functions;
-
ease of transfer through different transport mechanisms.
De-sign criteria
Theabove requirements were used to formulate the following design criteria:
Completeness
In any area of ISO/IEC 9636, the functionality specified by ISO/IEC 9636 should be complete in itself.
Conciseness
Redundant functions or parameters should be avoided.
Consistency
Contradictory functions should be avoided.
Extensibility
The ability to add new functions and generality to ISO/IEC 9636 should not be precluded.
Fidelity
The results and behaviour of functions should be well defined.
Implementability
A function should be able to be efficiently supported on most host systems andor graphics hardware.
Orthogonality
Independent functions for separate and noninteracting activities should be provided.
Predictability
The recommended or proper use of a standard function should guarantee the results of using that particular function.
Standard practice
Only those functions that reflect existing practice, that are necessary to support existing practice, or that are necessary
to support standards being developed concurrently should be standardized.

ISOAEC 9636-1: 1991 (E)
j) Usefulness
Functions should be powerful enough to perform useful tasks.
k) Well-structured
The number of assumptions that functions make about each other should be minimized. A function should have a
well-defined interface and a simply stated unconditional purpose. Multi-purpose functions and side effects should be
avoided.
Parts of the CGI functional specification
ISO/IEC 9636, the functional specification of the Computer Graphics Interface, consists of a number of parts presenting
portions of the CGI functionality, including an overview in this part of ISO/IEC 9636.
Table 1 - Parts of the CGI Functional Specification
Title
Part No.
~ Overview, profiles, and conformance
ISO/IEC 9636-l
ISO/IEC 9636-2 ~ Control
ISO/IEC 9636-3 output
ISO/IEC 9636-4 Segments
ISO/IEC 9636-5 Input and echoing
ISO/IEC 9636-6 Raster
This part of ISO/IEC 9636 gives a general overview and introduction to the basic concepts and principles of ISO/IEC 9636. It
includes a reference model, the relationship to other standards, and profiles. In addition, it contains overviews of each of the
subsequent parts. This part of ISO/IEC 9636 thus establishes the framework for all the parts of ISO/IEC 9636; it does not
contain functional descriptions.
The functional capability provided by the CGI is separate from the specification of any particular encoding format or language
binding.
vii
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INTERNATIONAL STANDARD
ISO/IEC 9636-l : 1991(E)
Information technology - Computer graphics -
Interfacing techniques for dialogues with graphical
devices (CGI) - Functional specification -
Part 1:
Overview, profiles, and conformance
1 Scope
ISO/IEC 9636 establishes the conceptual model, functional capability, and minimum conformance requirements of the
Computer Graphics Interface (CGI). It specifies design requirements for encodings of the CGI. ISO/IEC 9636 defines a set of
CGI functions that is expected to satisfy the following needs of a majority of the computer graphics community:
a) provide an interface standard for computer graphics software package implementors;
b) provide an interface standard for computer graphics device manufacturers and suppliers;
c) provide an inquiry and response mechanism for graphics device capabilities, characteristics, and states;
d) provide a standard graphics escape mechanism to access non-standard graphics device capabilities;
e) allow for future functional extension of the CGI.
In addition to the CGI functionality, device classes, and Foundation and Constituency Profiles are defined. The device classes
included in the CGI are output (OUTPUT), input (INPUT), and output/input (OUTIN). Profiles allow subsets of the CGI
functions and features to be defined to suit particular well identified groups of users. There is also provision for Constituency
Profiles to be registered after ISO/IEC 9636 is published. The Computer Graphics Interface (CGI) is a standard functional and
syntactical specification of the control and data exchange between device-independent graphics software and an
implementation of a CGI Virtual Device.
The syntax of the CGI, presented in ISO/IEC 9636, is an encoding-independent and binding-independent specification. Any
similarity of the examples or function specifications to a particular encoding technique or language is coincidental unless
explicitly stated otherwise.
The functions specified provide for the representation of a wide range of two-dimensional pictures and for control over their
display on a wide range of graphics devices. The functions are split into groups that perform device and CGI session control,
specify the data representations used, control the display of the picture, perform basic drawing actions, control the attributes of
the basic drawing actions, acquire data from input devices, and provide access to non-standard device capabilities.
This part of ISO/IEC 9636 gives an overview of ISO/IEC 9636, explains the relationship between its parts and their relation to
other standards, describes a reference model for graphics systems, and defines certain Foundation and Constituency Profiles.
ISO/IEC 9636-2, ISO/IEC 9636-3, ISO/IEC 9636-4, ISO/IEC 9636-5, and ISO/IEC 9636-6 specify the CGI functions for
different functional areas using an abstract notation.
ISO/IEC 9637 and ISO/IEC 9638 define standard data stream encodings, procedural library bindings, and single entry point
procedural bindings of the CGI.
1.1 Relationship of CGI to a computing environment
ISO/IEC 9636 describes graphical services provided by a Virtual Graphics Device. The model for description of these services
is expressed in terms of graphical capabilities of a single instance of a hypothetical graphics device. In all but the simplest of
ISO/IEC 9636-l : 1991 (E)
Scope Relationship of CGI to a computing environment
computing environments, CGI functions alone will not be sufficient to provide complete control over a device. Additional
functions, not included in ISO/IEC 9636, will likely be needed. Examples of such functions include
-
means to configure (sets of) physical devices to be accessed as CGI Virtual Devices;
-
means to control a device capable of offering CGI-defined services as well as other, non-CGI-defined services, such
as those implied by IS0 2022 and IS0 6429;
-
means to differentiate among separate instances of CGI Virtual Devices in the same computing environment;
means of defining or determining communication paths from CGI clients to CGI Virtual Devices.
In some cases, other standards exist that describe the functions required. For example, various communications standards
address the needs of the last point above. In other cases, no standards may exist, but the tasks indicated are outside the scope
of ISO/IEC 9636.
1.2 Position of CGI in a managed environment
There exists a large and growing family of computer controlled display systems that have the ability to act as if they are
multiple individual display devices. Resources, most notably the visible drawing surface resources, are coordinated by the
display system so that multiple non-cooperating client programs can each access the services of a separate individual device
while all are actually running in a single managed environment.
The graphical capabilities of the CGI Virtual Device may suffice, in some instances, as the basis for implementing a complex,
multiple-client display system. However, the complete needs of such a system are quite complex, include many non-graphical
services, and (as current practice shows) are quite technology dependent. The CGI does not, therefore, purport to be a
generally sufficient interface on which a managed display environment may be built. Rather, within a managed environment,
the CGI will be one of the managed interfaces in a way not visible to the CGI client without recourse to services not part of
ISO/IEC 9636. The use of the CGI as a managed interface within a managed display environment is not limited to raster
devices.
ISO/IEC 9636-l : 1991 (E)
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of
ISO/IEC 9636. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties
to agreements based on this part of ISO/IEC 9636 are encouraged to investigate the possibility of applying the most recent
editions of the standards listed below. Members of IEC and IS0 maintain registers of currently valid International Standards.
Information processing - IS0 7-bit coded character set for information interchange.
IS0 646 : 1983
Information processing - IS0 7-bit and B-bit coded character sets - Code extension techniques.
IS0 2022 : 1986
- Vocabulary - Part 13: Computer graphics.
IS0 2382-13 : 1984 Data processing
Information processing - Control functions for 7-bit and B-bit coded character sets.
IS0 6429 : 1988
- Graphical Kernel System (GKS) functional
IS0 7942 : 1985 Information processing systems - Computer graphics
description.
Information processing systems - Open systems interconnection - Basic reference model.
IS0 7498 : 1984
- Metafile for the storage and trans$er of picture
IS0 8632-l : 1987 Information processing systems - Computer graphics
description information - Part 1: Functional specification.
- Metafile for the storage and transfer of picture
IS0 8632-2 : 1987 Information processing systems - Computer graphics
description information - Part 2: Character encoding.
- Metafile for the storage and transfer of picture
IS0 8632-3 : 1987 Information processing systems - Computer graphics
description information - Part 3: Binary encoding.
- Graphical Kernel System for Three Dimensions
IS0 8805 : 1988 Information processing systems - Computer graphics
(GKS-3D) functional description.
- Part I: Encoding principles for picture
IS0 9282-l : 1988 Information processing - Coded representation of pictures
representation in a 7-bit or B-bit environment.
- Programmer’s Hierarchical Interactive
ISO/IEC 9592-l 1989 Information processing systems - Computer graphics
Graphics System (PHIGS) - Part 1: Functional description.
- Interfacing techniques for dialogues with graphical
ISO/IEC 9636-2 : 1991 Information technology - Computer graphics
devices (CGI) - Functional specification - Part 2: Control.
- InterJacing techniques for dialogues with graphical
ISO/IEC 9636-3 : 1991 Information technology - Computer graphics
devices (CGI) - Functional specification - Part 3: Output.
ISO/IEC 9636-4 : 1991 Information technology - Computer graphics - Interfacing techniques for dialogues with graphical
devices (CGI) - Functional specification -Part 4: Segments.
ISO/IEC 9636-5 : 1991 Information technology - Computer graphics - Interfacing techniques for dialogues with graphical
- Functional specification - Part 5: Input and echoing.
devices (CGI)
- Interfacing techniques for dialogues with graphical
ISO/IEC 9636-6 : 1991 Information technology - Computer graphics
- Functional specification - Part 6: Raster.
devices (CGI)
- Interfacing techniques for dialogues with graphical
ISO/IEC 9637-l : -I) Information technology - Computer graphics
devices (CGI) - Data stream binding - Part 1: Character encoding.
- Interfacing techniques for dialogues with graphical
ISO/IEC 9637-2 : -I) Information technology - Computer graphics
devices (CGI) - Data stream binding - Part 2: Binary encoding.
ISO/IEC TR 9973 : 1988 Information processing - Procedures for registration of graphical items.
Standard for Binary Floating Point Arithmetic.
ANSI/IEEE 754 -
l) To be published.
ISO/IEC 9636-l : 1991 (E)
3 Definitions and abbreviations
3.1 Organization of the definitions
The following list of definitions describes the usage of words or phrases which have been given special technical meaning in
the context of ISO/IEC 9636. These meanings are not in conflict with dictionary meanings or usage in other IS0 and IEC
standards. However, there are usually additional semantics associated with the words or phrases which are essential to
understanding ISO/IEC 9636.
The list of definitions is arranged in alphabetical order of main entry. Occasionally a term will be used with or without
optional qualification in the text; in such cases, the optional qualification appears in parentheses in the term. Under each main
entry, certain derived terms may also be covered; all such derived terms are underlined. With a few exceptions, where the
appropriate main heading may not be immediately obvious, derived terms do not have separate main entries. Where a phrase
appears in italic text, its definition may be as another main entry or it may be a derived term - in which case it will be found
either under an entry for one of its constituents (not necessarily its first), under another compound entry with the same first
constituent, or under an entry for another word with the same root.
3.2 Definitions
For the purposes of ISO/IEC 9636, the following definitions apply.
3.2.1 acknowledgement
An action performed automatically by a logical input device signals to the operator that an input operation has been
completed. Initially enabled by default, this action is controllable by the client using acknowledgement control. In a remote
echoing situation, the acknowledgement has to be explicitly performed by the client. Various acknowledgement may be
available and the client can select from these different styles of signalling.
3.2.2 active (for a LID)
A logical input device is active if events or sampling have been enabled or if request or echo request input is in progress;
otherwise, it is not active.
3.2.3 allowed latitude
There are a number of cases in which ISO/IEC 9636 identifies a limited set of allowed behaviours for functions or features and
allows implementors latitude to provide precisely one of this set. In such cases, a description table entry gives a client the
opportunity to inquire the implemented behaviour. ISO/IEC 9636 always identifies one of these allowed behaviours as a
preferred behaviour. This method of regulating implementation variability contrasts with that referred to as implementation
dependence. Where ISO/IEC 9636 allows latitude in the value of a state list default, then a particular value is identified as the
preferred default. An example is the default VDC Type, which has allowed latitude in its value, and a preferred default of
INTEGER.
3.2.4 appending (to a segment)
See under segment definition.
3.2.5 arming (a trigger)
An action which enables a trigger to be fired by the operator to signal the occurrence of something significant. A trigger
cannot be fired unless it has been armed. Triggers are armed for a logical input device while events are enabled for it and
while a request or echo request input operation is in progress.
3.2.6 aspect ratio
The ratio, using a uniform metric, of the width to the height (i.e. x to y) of a rectangular area, such as a VDC extent or a device
viewport.
3.2.7
aspect source flag (ASF)
Aspect source flags which are themselves attribute values indicate the source of other attribute values which determine aspects
of primitives or objects. If the value of a particular aspect source flag is INDIVIDUAL, then the attribute value for that
particular aspect is associated with the primitive or object. If the value of a particular aspect source flag is BUNDLED, then
ISO/IEC 9636-l : 1991 (E)
Definitions and abbreviations
Definitions
the corresponding bundle index attribute value associated with the primitive or object is used to access a bundle table UI find
the attribute value determining the aspect in question.
3.2.8 aspects (of primitive and object)
Characteristics determining the visual (rendered) appearance of primitives or objects are known as aspects. A particular aspect
of a particular primitive or object is determined by an attribute value which may be directly associated with it or indirectly
associated with it by means of a bundle index as determined by the appropriate aspect source flag. There are other
characteristics of primitives and objects which are determined by attribute values, but if these are not concerned with visual
appearance or are only specifiable directly (i.e. they cannot be bundled), they are not referred to as aspects.
association (of attribute values)
3.2.9
This refers to various steps in the graphic object pipeline where the connection between graphic objects and attribute values
relevant to their rendering is established. For aspects relevant to a given primitive type, the corresponding attribute values are
associated during the initial step of object creation and later, just before rendering, for those aspects for which the (already
associated) aspect source j7ag values are bundled. For objects stored in segments, the associated object transformation
attribute value can be modified by the concatenation of a segment transformation, which is a segment attribute, or a copy
transformation, which is a parameter to the copy segment function. Associated attribute values can be replaced by means of
the copy segment function and the inheritance filter.
association (of triggers with LIDS)
3.2.10
see under trigger association.
3.2.11 attribute function
A function which sets an attribute value in a state list. Unqualified, the term is used for functions which set primitive or object
attribute values. If other attributes are intended, the term will be appropriately qualified, e.g. segment attribute function or
raster attribute function.
3.2.12 attribute value
Certain characteristics of entities are determined by attribute values. When used without qualification, the term implies
primitive or object attribute value. All other uses of attribute value will be appropriately qualified such as segment attribute
value, raster attribute value, etc. Many primitive or object attribute values are directly concerned with rendered appearance
and determine aspects. Others may not be directly or at all concerned with rendered appearance (such as ASFs and pick
identifiers). When a single primitive forms a single object, there is no distinction between primitive attribute value and object
attribute value. However, when several primitives contribute to one object (compound text or closed figure), the primitive
attribute values are associated with each contributing primitive (see local attribute value) while object attribute values are
associated with the object as a whole (see global attribute vahe). As an example, auxiliary colour is a primitive (local)
attribute value for edges but an object (global) attribute value for interiors offill objects.
3.2.13 auxiliary colour
The auxiliary colour attribute value associated with an object is used in conjunction with the transparency attribute value. See
under transparency.
3.2.14 background colour
The colour used in preparing the drawing surface.
background colour (of mapped bitmap)
3.2.15
A controZ value that determines the full depth value to which the background pixels of a mapped bitmap are expanded when
they participate in raster operation functions.
3.2.16 binding
A binding is a (concrete) realization of an abstract functional specification in a programming language. This may be in terms
of a procedural library binding to a standard programming language with approximately one call per function or a
procedural single entrv Doint binding of the abstract functions with all input and output parameters. Procedural single entry
point bindings are based on data stream encodings; see encoding. In the absence of any clear context implying the contrary,
“procedural binding” or “binding” may be taken to refer to a procedural library binding.
3.2.17 bitblt
BIT aligned BLock Transfer. The transfer or combination of the pixel values in rectangular bitmap regions of bitmaps. The
CGI provides two and three operand bitblt functions where there are one or two source bitmap regions respectively, and a
destination bitmap region. Arbitrary logical combinations and some arithmetic combinations are supported by drawing mode.
See raster operation functions.

ISO/IEC 9636-l : 1991 (E)
Definitions and abbreviations Definitions
3.2.18 bitmap
A resource of the Virtual Device which may be viewed by the client as a rectangular array of pixels. This resource is available
only on devices offering the functional capability defined in ISO/IEC 9636-6. Some bitmaps are inherent resources of the
device; others can be defined by the client. CGI provides for full depth bitma where the values assignable to the individual
pixels span the total colour or grey scale capability of the device, and for mapped bitma where the values assignable to a
pixel are only “foreground” or “background”; it does not provide arbitrary variable depth b&nap capability. Any bitmap may
be selected as the drawing bitman which is the destination (drawing surface) for the rendering of (graphic) objects as well as
for raster operation functions. Bitmaps which are displayable bitmaps may also be selected as the w bitman.
3.2.19 bitmap region
see region.
3.2.20 blocked (of a queue)
A queue is said to be blocked if the client has taken specific action to prevent the entry of elements into it. Contrast with
oveflow where there may or may not be implicit system action to “block” a queue in overflow state.
3.2.21 boundary
The boundary of af’irr object consists of explicit boundary portions, implicit boundary portions, and clip boundary portions.
The boundary of a fill primitive consists of the mathematical locus of its defining perimeter. During closedfigure construction,
the mathematical locus of each line primitive used (including CONNECTING EDGE) and the boundary of each fill primitive
used defines an exDlicit boundarv Dortion. Implicit boundary nortions are those added automatically during closed figure
construction to ensure closure. (The interpretation of the significance of edge out flags in the POLYGON SET function means
that it can also introduce both explicit boundary portions and implicit boundary portions.) When a fill object undergoes locus
clipping, pieces of the original closed boundary lying outside the effective clip region are discarded and clip boundarv nortions
are added to maintain closure. Drawing surface clipping does not contribute any clip boundary portions. Clip and implicit
boundary portions have no associated attribute values. Edge portions correspond to the explicit boundary portions and are
rendered in accordance with their associated edge attribute values. Contrast with edge, and see also interior, realized edge, and
realized interior.
3.2.22 break action
A specific action by the operator to indicate that an input operation should be aborted. Contrast with firing (a trigger) and
with timeout.
3.2.23 bundle
Virtual Devices have a conceptual resource known as bundle tables. Bundle tables contain attribute values determining aspects
of primitives or objects. There are different bundle tvnes - one each for line, marker, text, (fill object) edge, and fill (object
interior) aspects. A bundle table consists of all bundles of a given type; each of which is uniquely identified by its index. For a
particular primitive or object, those aspects for which an attribute value from a
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