ISO/IEC 8632-2:1992

ISOAEC
INTERNATIONAL
STANDARD 8632-2
Second edition
1992-10-01
------.-.- -------
_ _____ -_ _ -__._._-. --_- - .--- ---------- -----.-. -_ .--.------ - -. _-.--.--.---. .---- -_----- ---_- .---. -__-_.- _.- .---. ---__.--------.----I_---
Information technology - Computer graphics -
Metafile for the storage and transfer of picture
description information -
Part 2:
Character encoding
Technologies de I’hforrnatior~ ---- Infographie -- M&fichier de stockage
et de fr-ansfert des ir~formations de description d’images -
Pat-tie 2: Codaqe des cat-act&-es
\
Reference number
ISCM EC 8632-2: 1992(E)
ISO/IEC 8632-2: 1992 (E)
CONTENTS
. . . . . . 1
1 Scope. . . . . . . . . . . . . . . . . . . . . .
. . . . . 2
.
2 Normative references . . . . . . . . . . . . . . . . .
.
. . . . . . . . .
. . . . . . . .
. .
3 Notational conventions
. . . . . * . . . .
. . . . . .
3.1 7-Bit and S-Bit code tables .
. . . . . .
3.2 Code extension techniques vocabulary l . . . . . . . . . .
. . . . . .
3.2.1 CO sets . . . v . . . . . . . . . . . . .
. . . . . .
3.2.2 Cl sets . . . . . . . . . . . . . . . . .
. . .
. . .
3.2.3 G-sets . . . . . . . . . . . . . . . . . .
. . . . . . 7
. . . Q . . . . .
4 Entering and leaving the metafile environment
. . . . . . 7
4.1 Implicitly entering the metafile environment . . . . . . . .
. . . . . .
4.2 Designating and invoking the CGM coding environment from IS0 2022
. . . . . . e . . . l
...... . .
5 Method of encoding opcodcs
. . . . . . . . . . . .
.
5.1 Encoding technique of the basic opcode set
. . . . . . . . . . . . .
......
5.2 Extension mechanism
. . . . . . . . . .
....... . . .
5.3 Opcode assignments
. . . . . . 14
. . . . . b .
6 Method of encoding parameters . . . . .
. . . . . 14
. . . . . . . .
6.1 Basic format . . . . . . . . .
. . . . . . . 15
. . . . . .
6.2 Bitstream format . . . . . . . .
. . . . . . . . . 16
. . . .
6.3 Coding integers . . . . . . . .
. . . . . . . * . . . 16
. .
6.4 Coding real numbers . ’ . . . . .
. 0 . . . . . 18
. . . . . .
6.5 Coding VDCs and points . . . . .
. . . . . . 18
. . . . . . .
6.6 Coding point list parameters . . . .
. . . . . . . 18
. . . . . .
6.6.1 Displacement mode . . . . .
. . . . . . . . . 19
. . . .
6.6.2 Incremental mode . . . . .
. . . . . . . . . . 22
. . .
6.6.3 Incremental mode encoding . .
. . . . . . 23
. . . . . . .
6.7 Colour specifiers . . . . . . . .
. . . . . . 24
. * . . . . .
6.8 Colour lists *
. . . . . . 25
. a . . . . .
6.8.1 Normal format*(cdding t&10) .
. . . . . . 25
. . . . . . .
6.8.2 Bitstream format (coding type=l)
. . . . . . . . . 25
. . . .
6.8.3 Runlength format (coding type=2)
. . . . . . . . . . . 25
.
6.8.4 Runlength bitstream format (coding type=3)
. . . . . . . 26
. . . . .
6.8.5 Examples . . . . . . . . . . .
. . . l . . . 27
. . . . . . . . .
6.9 String parameters
. . . . . . . . . 27
. . .
6.9.1 Overall string iaramkter format . . . .
. . . . . 27
6.9.2 Bit combinations permitted within string parameters of text elements
. . . . . 28
6.9.3 CO control within string parameters . . . . . . . . . .
. . . . . 28
6.9.4 Using G-sets in string parameters . . . . . . . . . .
0 lSO/lEC 1992
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 Copyriigkt Office l Case postale 56 l CH-1211 Genkve 20 l Switzerland
Printed in Switzerland
ISO/IEC 8632-2: 1992 (E)
Enumerated parameters . . . . . . . . . . . . . . . . . . . . . 29
6.10
. . . . . . . . . 29
Index parameters . . . . . . . . . . . . . .
6.11
. . . . . . . . . . . . . . 29
Data record parameters . . . . . - .
6.12
. . . . . . . . . . . . . . . 29
6.13 Coding VCs and viewport point parameters
. .
. . . . . . . . . . . . . . . 30
6.14 Name parameters . v . . . .
. . . 30
. . . . . . . . . . . . . . .
6.15 Compressed bitstream operands
. . . . 30
. . . . . . . . . . . . . .
6.16 Structured data record operands
. . . 0 . . . l . . . . . 30
6.17 Glyphmapping . . . . . . . . . .
. . . . 31
. . . . . . . . . . . . .
7 Character substitution . . . . . .
. . . . . . . . . . . . . . . . . 33
8 Representation of each element . . .
. . . . . . . . . . . . . . . . . 35
8.1 Delimiter elements . . . . .
BEGINMETAFILE . . . . . . . . . . . . . . . . . . . 35
8.1.1
ENDMETAFILE . . . . . . . . . . . . . . . . . . . . 35
81.2
. . . . 35
8.1.3 BEGINPICTURE . . . . . . . . . . . . . . . .
. . . * . . . 35
8.1.4 BEGIN PICTURE BODY . . . . . . . . . . .
. . . . . . . . . . 35
8.15 ENDPICTURE . l . . . . . . . . .
. . . . . . . . . . . . . 35
8.1.6 BEGINSEGMENT . . . . . . .
. . . . . . . . . . . . . . . . . 36
8.1.7 ENDSEGMENT . . e
BEGINFIGURE . . . . . . . . . . . . . . . . . . . . 36
8.1.8
8.1.9 ENDFIGURE . . . . . . . . . . . . . . . . . . . 0 . 36
8.1.10 BEGIN PROTECTION REGION . . . . . . . . . . . . . . . 36
8.1.11 END PROTECTION REGION . . . . . . . . . . . . . . . . 36
8.1.12 BEGIN COME’OUNDLINE . . . . . . . . . . . . . . . . . 36
. . . . . . . . . . . . . . . 36
8.1.13 END COMPOUNDLINE . . .
BEGIN COMPOUND TEXT PATH . . . . . . . . . . . . . . . 36
8.1.14
END COMPOUND TEXT PATH . . . . . . . . . . . . . . . 36
8.1.15
8.1.16 BEGINTILE ARRAY . . . . . . . . . . . . . . . . . . . 36
ENDTILE ARRAY . . . . . . . . . . . . . . . . . . . 37
8.1.17
8.2 Metafile descriptor elements . . . . . . . . . . . . . . . . . . 38
8.2.1 METAFILE VERSION . . . . . . . . . . . . . . . . 38
. . . . . . . . . . . . 38
8.2.2 METAFILE DESCRIPTION . . . .
. . . . * . . . . . . . . . . 38
8.2.3 VDCTYPE . . . . . .
8.2.4 INTEGER PRECISION . . . . . . . . . . . . . . . . . 38
8.2.5 REAL PRECISION . . . . . . . . . . . . . . . . . . . 38
. . . . . . . . . . . . .
8.2.6 INDEXPRECISION . . . . . 39
8.2.7 COLOUR PRECISION . . . . . . . . . . . . . . . 39
8.2.8 COLOUR INDEX PRECISION . . . . . . . . . . . . . . . 40
8.2.9 MAXIMUM COLOUR INDEX . . . . . . . . . . . . . . . 40
8.2.10 COLOUR VALUE EXTENT . . . . . . . . . . . . . . . . 40
8.2.11 METAFILE ELEMENT LIST . . . . . . . . . . . . . . . 40
8.2.12 METAFILE DEFAULTS REPLACEMENT . . . . . . . . . . . . 41
8.2.13 FONTLIST . . . . . . . . . . . . . . . . . . . . . . 41
8.2.14 CHARACTER SET LIST . . . . . . . . . . . . . . . . . . 41
. . . . . . .
8.2.15 CHARACTER CODING ANNOUNCER . . . . . . 42
. . . . .
8.2.16 NAME PRECISION . . . . . . * . . . . . 42
. .
8.2.17 MAXIMUM VDC EXTENT . . . . . . . . . . 42
. . .
8.2.18 SEGMENT PRIORITY EXTENT. : : : . . . . . . . . . 42
. . .
8.2.19 COLOUR MODEL . . . . . . . . . . . . . . . . . 42
8.2.20 COLOUR CALIBRATION . . . . . . . . . . . . . . . . . 42
. . . 44
8.2.2 1 FONT PROPERTIES . . . . . . . . . . . . . . . .
8.2.22 GLYPH MAPPING . . . . . . . . . . 46
. . . . . . .
8.2.23 SYMBOL LIBRARY LIST’ . . . . . . . . . . . . . . l . . 47
. . .
ISO/IEC8632=2:1992(E)
8.3 Picture descrbtor elements . . . . . . . . . . . . . . . . . . . . 48
................ 48
8.3.1 SCALiNG MODE
............. 48
8.3.2 COLOUR SELECTION-MODE
............. 48
LINE WIDTH SPECIFICATION MODE
8.3.3
............
MARKER SIZE SPECIFICATION MODE
8.3.4
.............
8.3.5 EDGE WIDTH SPECIFICATION MODE
.....................
8.3.6 VDCEXTENT
................. 49
BACKGROUND COLOUR
8.3.7
................... 49
DEVICE VIEWPORT
8.3.8
...........
8.3.9 DEVICE VIEWPORT SPECIFICATION MODE
...............
8.3.10 DEVICE VIEWPORT MAPPING
.................
8.3.11 LINE REPRESENTATION
................
8.3.12 MARKER REPRESENTATION
................. 50
8.3.13 TEXT REPRESENTATION
................. 5 1
8.3.14 FILL REPRESENTATION
.................
5 1
8.3.15 EDGE REPRESENTATION
...........
8.3.16 INTERIOR STYLE SPECIFICATION MODE
............. 52
8.3.17 LINE AND EDGE TYPE DEFINITION
................ 52
8.3.18 HATCH STYLE DEFINITION
............. 53
8.3.19 GEOMETRIC PATTERN DEFINITION
r.4
....................... 34
8.4 Control elements
................ 54
8.4.1 VDC INTEGER PRECISION
..................
8.4.2 VDC REAL PRECISION
..................
8.4.3 AUXILIARY COLOUR
.................... 55
8.4.4 TRANSPARENCY
................... 55
8.4.5 CLIPRECTANGLE
.................... 55
8.4.6 CLIP INDICATOR
.................. 55
8.4.7 LINE CLIPPING MODE
................ 56
8.4.8 MARKER CLIPPING MODE
..................
8.4.9 EDGE CLIPPING MODE
..................... 56
8.4.10 NEWREGION
................ 56
8.4.11 SAVE PRIMITIVE CONTEXT
............... 56
8.4.12 RESTORE PRIMITIVE CONTEXT
.............. 56
8.4.13 PROTECTION REGION INDICATOR
.............. 57
8.4.14 GENERALIZED TEXT PATH MODE
..................... 57
8.4.15 MITRELIMIT
............... 57
8.4.16 TRANSPARENT CELL COLOUR
................... 58
8.5 Graphical primitive elements
...................... 58
8.5.1 POLYLINE
.................. 58
8.5.2 DISJOINT POLYLINE
.................... 58
8.5.3 POLYMARKER
.......................
8.5.4 TEXT.
...................
8.5.5 RESTRICTED TEXT
..................... 59
8.5.6 APPENDTEXT
...................... 59
8.5.7 POLYGON
.................... 59
8.5.8 POLYGONSET
..................... 59
8.5.9 CELLARRAY
............. 6 1
8.5.10 GENERALIZED DRAWING PRIMITIVE
..................... 61
8.5.11 RECTANGLE
....................... 61
8.5.12 CIRCLE
................. 61
8.5.13 CIRCULAR ARC 3 POINT
.............. 61
8.5.14 CIRCULAR ARC 3 POINT CLOSE
................. 62
8.515 CIRCULAR ARC CENTRE
ISO/IEC 8632-2: 1992 (E)
. . . . . . .
8.5.16 CIRCULAR ARC CENTRE CLOSE . . . . . . . 62
. . . . . . . 62
8.5.17 ELLIPSE . . . . . . . . . . . . . . . .
ELLIPTICAL ARC . . . . . . . . . . . . . . . . . . . . 62
8.5.18
ELLIPTICAL ARC CLOSE . . . . . . . . . . . . . . . . 63
8.5.19 .
. . . . . . .
8.5.20 CIRCULAR ARC CENTRE REVERSED . . . . . . 63
.
8.5.21 CONNECTINGEDGE . . . . . . . . . . . . . . . . . 63
. . .
8.5.22 HYPERBOLIC ARC . . . . . . . . . . . . . . . . 63
. . . . .
8.5.23 PARABOLIC ARC . . . . . . . . . . . . . . . 63
. . . . . . . . . . . 64
8.5.24 NON-UNIFORM B-SPLINE . . . . . .
. . . . . .
8.5.25 NON-UNIFORM RATIONAL B-SPLINE . . . . . . . 64
. . . . . . . . . . .
8.5.26 POLYBEZIER . . . . . . . . . . 64
. . . . . . . . . . . . . .
8.5.27 POLYSYMBOL . . . . . . 65
BITONALTILE . . . . . . . . . . . . . . . . . . . . 65
8.5.28
8.5.29 TILE . . . . . . . . . . . . . . . . . . . . . . . . 66
8.6 Attribute elements . . . . . . . . . . . . . . . . . . . . . . 67
8.6.1 LINEBUNDLEINDEX . . . . . . . . . . . . . . . . . . 67
8.6.2 LINETYPE . . . . . . . . . . . . . . . . . . . . . . 67
8.6.3 LINE WIDTH . . . . . . . . . . . . . . . . . . . . . 67
.
8.6.4 LINECOLOUR . . . . . . . . . . . . . . . . . . . 0 67
. . .
8.6.5 MARKER BUNDLE INDEX . . . . . . . . . . . . . . 67
8.6.6 MARKERTYPE . . . . . . . . . . . . . . . . . . . . 67
. . . . . . . .
8.6.7 MARKERSIZE . . . . . . . . . . . . . 68
. . . . . . . . . . . .
8.6.8 MARKERCOLOUR . . . . . . 68
TEXTBUNDLEINDEX . . . . . . . . . . . . . . . . . . 68
8.6.9
8.6.10 TEXTFONTINDEX . . . . . . . . . . . . . . . . . . .
8.6.11 TEXTPRECISION . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . 68
8.6.12 CHARACTER EXPANSION FACTOR
8.6.13 CHARACTERSPACING . . . . . . . . . . . . . . . . . . 69
8.6.14 TEXT COLOUR . . . . . . . . . . . . . . . . . . 69
. . .
8.6.15 CHARACTER HEIGHT . . . . . . . . . . . . . 69
. . . . . . . . . . . .
8.6.16 CHARACTERORIENTATiON . . . . 69
TEXT PATH . . . . . . . . . . . . . . . . . . .
8.6.17 69
8.6.18 TEXT ALIGNME& . . o . . . . . . . . . . . . . . 69
8.6.19 CHARACTERSETINDEX . . . . . . . . . . . . . . . . . 70
.
8.6.20 ALTERNATE CHARACTER SET INDEX . . . . . . . . . . . 70
FILLBUNDLEINDEX . . . . . . . . . . . . .
8.6.21 70
8.6.22 . . . . . . . . . . . .
INTERIOR STYLE . 70
8.6.23 FILL COLOUR . . . . . . . . . . . . 71
.........
. . . . . . . . . . .
8.6.24 HATCH INDEX . . 71
. . . . . . . . . . . .
8.6.25 PATTERN INDEX . 71
8.6.26 EDGEBUNDLEINDEX . . . . . . . . . . . . . 71
8.6.27 EDGE TYPE . . . . . . . . . . . . . 71
.
8.6.28 EDGE WIDTH . . . . . . . . . . . . 72
. . . . . . . . . . .
8.6.29 EDGE COLOUR . . 72
8.6.30 EDGE VISIBILITY . . . . . . . . . . . . . . . . 72
. . . . .
8.6.3 1 FILLREFERENCE POiNT . . . . . . . . 72
. . . . . . .
8.6.32 PATTERN TABLE . . . . . . 72
. . . . . . . .
8.6.33 PATTERN SIZE . . . . . 72
. . . . . . . . . . . .
8.6.34 COLOUR TABLE . 73
..... . . . . . . . . . . . .
8.6.35 ASPECTSOURCEFLAGS 73
8.6.36 PICK IDENTIFIER . . . . . . . . . . . . . 74
8.6.37 LINE CAP . . . . . . . . . . . . . 74
8.6.38 LINE JOIN . . . . . . . . . . . . . 74
V
ISO/IEC 8632-2: 1992 (E)
. . . . . . . . .
. . . . . .
.
LINE TYPE CONTINUATION
8.6.39
. . . . . . . . .
. . . . . . .
8.6.40 LINE TYPE INITIAL OFFSET
. . . . . . . . .
. . . . . . .
8.6.41 TEXT SCORETYPE . . l
. . . . . . . 75
. . . . . . .
. .
8.6.42 RESTRICTED TEXT TYPE .
. 75
. . . . . . . . . . . . . . .
8.6.43 INTERPOLATED INTERIOR
. . . . . . . 76
. * . . . * . . .
8.6.44 EDGECAP . . . . . .
. . . . . . . 76
. . . . . . . . .
8.6.45 EDGEJOIN . . . . . .
. . . . . . . . . 76
. . . . . . .
EDGE TYPE CONTINUATION
8.6.46
l . . . . . 77
. . . . . . . . . .
8.6.47 EDGE TYPE INITIAL OFFSET
* . . . . . . . . 77
. . . . . . .
8.6.48 SYMBOL LIBRARY INDEX
. . . . . . . . . 77
. . . . . . . .
8.6.49 SYMBOLCOLOUR l .
. . . . . . . . . . . . . . 77
. . .
8.6.50 SYMBOLSIZE . . . .
. . . . . . . . . . . . . . . .
SYMBOL ORIENTATION .
8.6.5 1
. * 78
. . . . . . . . . . . . . .
.
8.7 Escape elements . . . . . .
. . . . . . . . . . . . . . . .
8.7.1 ESCAPE . . e . . . .
. 78
. . . . . . . . . . . . . . . .
8.7.2 DOMAINRING . . .
. * . . . 79
. . . . . . . . . . . .
8.8 External elements . . . . .
. . . . . . . 79
. . . . . . . . . .
8.8.1 MESSAGE . . . . .
. . . . . . . . . . . . . 79
. . . .
8.8.2 APPLICATION DATA .
. . . * . . . . . 80
. . . . . . 0 .
8.9 Segment elements . . . . .
. . . . . . . . . . . . . 80
. . . .
8.9.1 COPY SEGMENT . . .
. . . . . . . . . . . . . 80
. . . .
8.9.2 INHERITANCE FILTER .
. . . . . . . . . . . . . . . 82
8.9.3 CLIP INHERITANCE . . . .
. . . . . . . . . . . . . . . 82
8.9.4 SEGMENT TRANSFORMATION
. . . .
. . . . . . . . . . . 82
8.9.5 SEGMENT HIGHLIGHTING
. . . . . . . . . . . . . . . 83
8.9.6 SEGMENT DISPLAY PRIORITY*
. . . . . . . . . . . . . . . . 83
8.9.7 SEGMENT PICK PRIORITY
. . . . . . . . . . . . . . 84
9 Defaults . . . . . . . . . . . . .
. 85
10 Conformance . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . l . 86
A Formal grammar . . . . . . . . .
vi
ISO/IEC 8632-2: 1992 (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, ISOIIEC 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 ISOIIEC 8632-2 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information
technology.
This second edition cancels and replaces the first edition (IS0 8632-2: 1987), which has been technically revised.
ISOIIEC 8632 consists of the following parts, under the general title Information technology - Computer
graphics -Metafile for the storage and transfer of picture description information :
Part I : Functional specijkation
Part 2: Character encoding
Part 3: Binary encoding
Part 4: Clear text encoding
Annex A forms an integral part of this part of ISO/IEC 8632.
vii
ISO/IEC 8632-2: 1992 (E)
Introduction
0.1 Purpose of the character encoding
The Character Encoding of the Computer Graphics Metafile (CGM) provides a representation of the
Metafile syntax intended for situations in which it is important to minimize the size of the metafile or
transmit the metafile through character-oriented communications services. The encoding uses compact
representation of data that is optimized for storage or transfer between computer systems.
If minimizing the processing overhead is more important than data compaction, an encoding such as the
Binary Encoding contained in ISO/IEC 8632-3 may be more appropriate. If human readability is the most
important criterion, an encoding such as the Clear Text Encoding in ISO/IEC 8632-4 may be more
appropriate.
0.2 Objectives
This encoding was designed with the following objectives:
regular syntax: All elements of the metafile should be encoded in a uniform way so that parsing
a>
the metafile is simple;
compactness: The encoding should provide a highly compact metafile, suitable for systems with
b)
restricted storage capacity or transfer bandwidth;
extensibility: the encoding should allow for future extensions;
C>
transportability: the encoding should be suitable for use with transport mechanisms designed for
d)
character-oriented data based on a standard national character set derived from ISO/IEC 646.
0.3 Metafile characteristics
Each CGM command follows a simple regular syntax. Thus, new commands can be added in a future revi-
sion of ISO/IEC 8632 such that existing CGM interpreters can recognize (and ignore) the new commands
Also, new operands can be added to existing commands in the future revision of the standard such tha
existing CGM interpreters can recognize (and ignore) the additional operands.
Each CGM operand follows a simple regular syntax. Operands are variable in length. This permits smal
values to be represented by the smallest number of bytes.
. . .
Vlll
ISO/IEC 8632-2: 1992 (E)
Introduction
Metafile characteristics
A certain range of operand values of standard commands have been reserved for private use; the remaining
range is either standardized or reserved for future standardization.
0.4 Relationship to other International Standards
The Character Encoding has been developed in collaboration with the IS0 subcommittee responsible for
character sets and coding, ECMA, and CEPT. The encoding conforms to the rules for code extension
specified in IS0 2022 in the category of complete coding system.
The representation of character data in this part of ISO/IEC 8632 follows the rules of ISO/IEC 646 and IS0
2022.
For certain elements, the CGM defines value ranges as being reserved for registration. The values and t.he.ir
meanings will be defined using the established procedures (see ISO/IEC 8632-1, sub-clause 4.12.)
1x
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INTERNATIONAL STANDARD ISO/IEC 8632-2: 1992 (E)
Information technology - Computer graphics - Metafile for
the storage and transfer of picture description information -
Part 2 :
Character encoding
1 Scope
This part of ISO/IEC 8632 specifies a character encoding of the Computer Graphics Metafile. For each of
the elements specified in ISO/IEC 8632-1 an encoding is specified.
This encoding of the Computer Graphics Metafile provides a highly compact representation of the metafile,
suitable for applications that require the metafile to be of minimum size and suitable for transmission with
character-oriented transmission services.

ISO/IEC 8632-2: 1992 (E)
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of
this part of ISO/IEC 8632. 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 8632 are encouraged to investi-
gate 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.
IS0 7-bit coded character set for information interchange.
ISOLIEC 646: 199 1, Information technology -
IS0 2022: 1986, Information processing - IS0 7-bit and S-bit coded character sets - Code extension techniques.
Procedure for registration of escape sequences.
IS0 2375: 1985, Data processing -
Control functions for 7-bit and &bit coded character sets.
IS0 6429: 1988, Information processing -
ECMA 96, Graphics Data Syntax for a multiple Workstation Integace.
CEPT, Revision of T/CD 6.1 Videotex Presentation Layer Data Syntax.

ISO/IEC 8632-2: 1992 (E)
3 Notational conventions
3.1 7,Bit and &Bit code tables
The bits of the bit combinations of the 7-bit code are identified by b7, b6, b5, b4, b3, b2, and bl, where b7
is the highest-order, or most-significant, bit and bl is the lowest-order, or least-significant, bit.
The bit combinations may be interpreted to represent integers in the range 0 to 127 in binary notation by
attributing the following weights to the individual bits:
.
Bit .
b6 b5 b4 b3 b2 bl
b7
.
. 64 32 16 8 4 2 1
Weight .
In this part of ISO/IEC 8632, the bit combinations are identified by notation of the form x/y, where x is a
number in the range 0 to 7 and y is a number in the range 0 to 15. The correspondence between the nota-
tions of the form xl/y and the bit combinations consisting of the bits b7 to bl is as follows:
- x is the number represented by b7, b6, and b5 where these bits are given the weights 4, 2, and 1
respectively;
- y is the number represented by b4, b3, b2, and bl where these bits are given the weights 8,4,2, and
1 respectively.
The notations of the form x/y are the same as those used to identify code table positions, where x is the
column number and y is the row number.
A 7-bit code table consists of 128 positions arranged in eight columns and sixteen rows. The columns are
numbered 0 to 7 and the rows are numbered 0 to 15. Figure 1 shows a 7-bit code table.
“l/l 1” refers to the bit combination in column 1, row 11 of the code
An example illustrates the 7-bit code:
table, binary 0011011.
The bits of the bit combinations of the 8-bit code are identified by b8, b7, b6, b5, b4, b3, b2, and bl, where
b8 is the highest-order, or most-significant, bit and bl is the lowest-order, or least-significant, bit.
The bit combinations may be interpreted to represent integers in the range 0 to 255 in binary notation by
attributing the following weights to the individual bits:
.
Bit
.
b8 b7 b6 b5 b4 b3 b2 bl
.
. 128 64 32 16 8 4 2 1
Weight .
Using these weights, the bit combinations of the 8-bit code are interpreted to represent numbers in the range
0 to 255.
In this part of ISO/IEC 8632, the bit combinations are identified by notation of the form xxIyy, where XX and
yy are numbers in the range 00 to 15. The correspondence between the notations of the form xx/yy and the
bit combinations consisting of the bits b8 to bl is as follows:
- xx is the number represented by b8, b7, b6, and b5 where these bits are given the weights 8,4, 2, and
1 respectively;
- yy is the number represented by b4, b3, b2, and bl where these bits are given the weights 8,4, 2, and
1 respectively.
The notations of the form ;“IxIyy are the same as those used to identify code table positions, where XX is the
column number and yy is the row number. An 8-bit code table consists of 256 positions arranged in sixteen
columns and sixteen rows. The columns and rows are numbered 00 to 15. Figure 2 shows an 8-bit code
ISOlIEC 8632-2: 1992 (E)
Notational conventions
7-Bit and &Bit code tables
table.
An example illustrates the 8-bit code: 04/01 represents the 8-bit byte 01000001, whereas 4/l represents the
7-bit byte 1000001.
3.2 Code extension techniques vocabulary
certain terms imported from other
In describing the characters that may occur within string parameters,
standards (e.g., IS0 2022) are useful. In the context of the CGM, these terms, and the concepts to which
they refer, apply only within the string parameters of the TEXT, APPEND TEXT, and RESTRICTED
TEXT metafile elements.
3.2.1 CO sets
A CO set is a set of 30 control characters represented in a 7-bit code by O/O to l/15, except O/14 and O/l5
which shall be unused, and in an 8-bit code by OO/OO to 01/15, except 00/14 and 00/15 which shall be
unused. CO sets occupy columns 0 and 1 of a 7-bit code table or columns 00 and 01 of an 8-bit code table.
The meanings of CO controls within string parameters are described in 6.9.3.
3.2.2 Cl sets
A Cl set is a set of up to 32 control characters represented by bit combinations OS/O0 to 09/15 in an 8-bit
In a 7-bit code the Cl control functions
code. Cl sets occupy columns 08 and 09 of the 8-bit code table.
are represented by 2-byte escape sequences. This CGM encoding reserves the bit combinations 9/8 and
9/12 (ESC 5/8 and ESC 5/12 in a 7-bit environment, ESC = l/l 1); these shall not be part of the content of
string parameters. Other Cl control characters from other standards, such as IS0 6429, may be used within
string parameters by agreement between the interchanging parties.
3.2.3 G-sets
The G-sets (GO, Gl, G2, G3) are coded character sets of 94 or 96 characters. CHARACTER SET INDEX
designates which character set is to be the GO set. ALTERNATE CHARACTER SET INDEX designates a
character set to be used as both the Gl and G2 sets. The G-sets may be “invoked into” (caused to occupy)
columns 2 through 7 of a 7-bit code table, or columns 02 through 07 and 10 through 15 of an 8-bit code
table. This encoding of the CGM uses the GO and Gl/G2 sets within string parameters. The G3 set may be
used within the string parameters of conforming metafiles; this requires selection of the extended 7-bit or
extended 8-bit mode in the CHARAmR CODING ANNOUNCER. The CGM does not provide an ele-
ment to explicitly designate the G3 sets; this may be done within a text string in accordance with IS0 2022,
or by other means agreed upon by the interchanging parties.

ISO/IEC 8632-2: 1992 (E)
Code extension techniques vocabulary
Notational conventions
A G-SET OF
94 OR 96
BIT COMBINATIONS
Figure l- The 7-bit code table

ISO/IEC 8632-2: 1992 (E)
Code extension techniques vocabulary Notational conventions
02 03 04 05 06 07
00 01 08 09
02/q
"GR" SET C
co "GL" SET OF
7 Cl
94 OR 96
94 OR 96
SET SET
BIT COMBINAT ONS
BIT COMBINATIONS
IO?. 15 I15/ 15
Figure 2 - The S-bit code table

ISO/IEC 8632-2: 1992 (E)
4 Entering and leaving the metafile environment
4.1 Implicitly entering the metafile environment
The CGM coding environment may be entered implicitly, by agreement between the interchanging parties.
This is suitable only if there is not to be any interchange with services using other coding techniques.
4.2 Designating and invoking the CGM coding environment from IS0 2022
For interchange with services using the code extension techniques of IS0 2022, the CGM coding environ-
ment shall be designated and invoked from IS0 2022 environment by the following escape sequence:
ESC 215 F
where ESC is the bit combination l/l 1, and F refers to a bit combination that will be assigned by the IS0
Registration Authority for IS0 2375.
The first bit combination occuring after this escape sequence will then represent the opcode of a CGM
metafile element.
After the end of one or more metafiles (i.e., after the END METAFILE clement) or between pictures (i.e.,
after the END PICTURE element), the following escape sequence may be used to return to the IS0 2022
coding environment:
ESC 215 4/O
This not only returns to the IS0 2022 coding environment, but also restores the designation and invocation
of coded character sets to the state that existed prior to entering the CGM coding environment with the ESC
2/5 F sequence. (The terms “designation” and “invocation” arc defined in IS0 2022.)

ISO/IEC 8632-2: 1992 (E)
5 Method of encoding opcodes
Each metafile element is composed of one opcode and parameters as required. The opcodcs are coded as a
sequence of bit combinations from columns 2 and 3 of the code chart. The encoding technique supplies:
- the basic opcode set;
- extension opcode sets.
5.1 Encoding technique of the basic opcode set
The basic opcode set consists of single-byte and double-byte opcodes. Single-byte opcodes are from
column 2 of the code chart. Bits b4 to bl are used to encode the opcode. The format is as follows:
b8 bl
+-+-- -- -+- -- -- --+
1x10 1 Olb b b bl
+-+-----+-------+
The “X” bit (bit b8) is the parity bit (or omitted bit) in a 7-bit environment. In an 8-bit environment it is 0.
For double-byte opcodes the first byte is from column 3 and the second byte is from column 2 or 3 of the
code chart. Bits b4 to bl of the first byte and bits b5 to bl of the second byte are used to encode the
opcode:
bl
b8 bl b8
+-+-----+-------+ +-+---+---------+
1x10 1 lib b b bj 1x10 lib b b b bl
+-+-----+------+ +-+---+---------+
The bit combination 3/15, the EXTEND OPCODE SPACE (EOS) allows extension of the basic opcode
space (see 5.2).
The basic opcode set, supplied by this encoding technique consists of 496 opcodes, being:
- 16 single-byte opcodes (from column 2);
- x 32 = 480 double-byte opcodes (first byte from column 3 bit combination 3/15, second
15 except
byte from column 2 or 3).
5.2 Extension mechanism
The basic opcode set can be extended with an unlimited number of extension opcode sets by means of the
EXTEND OPCODE SPACE code (EOS, 3/15).
The N-th extension opcode set consists of opcodes of the basic opcode set, prefixed with n times the code
EOS. The three possible formats of an opcode from the N-th extension opcode set are
Opcode format Extension codes Basic opcode set codes
1 . <2/x>
n times
ISO/IEC 8632-2: 1992 (E)
Extension mechanism
Method of encoding opcodes
<3/y> <2lz>
n times
. <3/y> <3/z>
------- I
I
I
n times
= 3115
X = 0,1,.,15
= 0,1,.,14
Y
Z = 0,1,.,15
n = OJ,.
n = 0 selects the basic opcode set.
n = 1 selects the first extension opcode set.
n = N selects the N-th extension opcode set.
The number of opcodes supplied by this encoding technique (basic opcode set plus extension opcode sets)
is 496*(n+l), where n is the number of extension sets. (Each extension set has 496 opcodes - 16 single-
byte opcodes plus 480 double-byte codes.)
5.3 Opcode assignments
Table 1 lists the opcode assignments for the CGM elements. All opcodes are from the basic opcode set.
They are organized as follows: single-byte opcodes are assigned to Graphical Primitive elements except for
some of the Circular and Elliptical output elements, where double-byte opcodes with combination 314 for
the first byte are assigned. All other metafile elements have double-byte opcodes with the following bit
combinations for the first byte:
for Delimiter Elements
for Metafile Descriptor Elements
for Picture Descriptor Elements
for Control Elements
315 and 316 for Attribute Elements
for Escape and External Elements
3/7
for Segment Control Elements and Segment Attribute Elements
ISO/IEC 8632-2: 1992 (E)
Opcode assignments Method of encoding opcodes
Table 1 - Opcodes for metafile elements
7-Bit coding S-Bit coding
Opcode
03/o 02/o
BEGIN METAFILE opcode 3/O 2/O
END METAFILE opcode 03/o 02/l
3/O 211
BEGIN PICTURE opcode 03/o 0212
3/O 212
BEGIN PICTURE BODY opcode 03/O 0213
3/O 213
END PICTURE opcode 03/O 0214
3/o 214
BEGIN SEGMENT opcode 03/o 0215
310 215
END SEGMENT opcode 03/O 0216
3/o 216
BEGIN FIGURE opcode 03/O 0217
3/o 217
END FIGURE opcode 03/o 02/s
310 218
2112 03/O 02112
BEGIN PROTECTION REGION opcode 310
2113 03/O 02113
END PROTECTION REGION opcode 3/o
BEGIN COMPOUND LINE opcode 2114 03/O 02114
END COMPOUND LINE opcode 2115 03/O 02115
BEGIN COMPOUND TEXT PATH opcode 03/O 03/o
310 310
END COMPOUND TEXT PATH opcode 03/O 0311
310 311
BEGIN TILE ARRAY opcode 03/O 03/2
3/o 312
END TILE ARRAY opcode 03/o 0313
3/O 313
METAFILE VERSION opcode 03/l 02/o
3/l 2/o
METAFILE DESCRIPTION opcode 03/l 02/l
311 211
VDC TYPE opcode 03/l 0212
311 212
INTEGER PRECISION opcode 311 213 03/l 0213
REAL PRECISION opcode 311 214 03/l 0214
INDEX PRECISION opcode 0215
311 215 0311
COLOUR PRECISION opcode 03/l 0216
311 216
COLOUR INDEX PRECISION opcode 03/l 0217
311 217
MAXIMUM COLOUR INDEX opcode 03/l 0218
311 218
COLOUR VALUE EXTENT opcode 03/l 0219
311 219
METAFILE ELEMENT LIST opcode 2110 03/l 02110
BEGIN METAFILE DEFAULTS REPLACEMENT opcode 2111 0311 02/H
END METAFILE DEFAULTS REPLACEMENT opcode 311 03/l 02112
FONT LIST opcode 2113 0311 02113
CHARACTER SET LIST opcode 2114 03/l 02114
CHARACTER CODING ANNOUNCER opcode 2115 0311 02115
NAME PRECISION opcode 03/l 03/o
311 310
MAXIMUM VDC EXTENT opcode 0311 03/l
311 311
SEGMENT PRIORITY EXTENT opcode 03/l 0312
311 312
COLOUR MODEL opcode 03/l 0313
3/l 313
COLOUR CALIBRATION opcode 03/l 0314
311 314
FONT PROPERTIES opcode 03/l 0315
311 315
GLYPH MAPPING opcode 316 03/l 0316
0311 0317
SYMBOL LIBRARY LIST opcode 311 317
ISO/IEC 8632-2: 1992 (E)
Method of encoding opcodes Opcode assignments
- Opcodes for metafile elements (continued)
Table 1
7-Bit coding S-Bit coding
Opcode
SCALING MODE opcode 312 2/o 0312 0210
COLOUR SELECTION MODE opcode 312 211 0312 02/l
LINE WIDTH SPECIFICATION MODE opcode 312 212 0212
MARKER SIZE SPECIFICATION MODE opcode 0312
312 213 0213
EDGE WIDTH SPECIFICATION MODE opcode 214 0312 0214
VDC EXTENT opcode 0312 0215
312 215
BACKGROUND COLOUR opcode 0312 0216
312 W3
DEVICE VIEWPORT opcode 312 217 0312
02/7
DEVICE VIEWPORT SPECIFICATION MODE opcode 0312
312 218 0218
DEVICE VIEWPORT MAPPING opcode 0312
312 219 0219
LINE REPRESENTATION opcode 2110 0312 02110
MARKER REPRESENTATION opcode 2111 0312 02/l 1
TEXT REPRESENTATION opcode 2112 0312 02112
FILL REPRESENTATION opcode 2113 0312 02113
EDGE REPRESENTATION opcode 0312 02114
INTERIOR STYLE SPECIFICATION MODE opcode 312 0312 02115
LINE AND EDGE TYPE DEFINITION opcode 0312 0310
312 3/O
HATCH STYLE DEFINITION opcode 0312 03/l
312 311
GEOMETRIC PATTERN DEFINITION opcode 0312 0312
312 312
VDC INTEGER PRECISION opcode 0313 02/o
313 2/O
VDC REAL PRECISION opcode 0313 02/l
313 211
AUXILIARY COLOUR opcode 313 212 0313 0212
TRANSPARENCY opcode 313 213 0313 0213
CLIP RECTANGLE opcode 0313 0214
313 214
CLIP INDICATOR opcode 0313 0215
313 215
LINE CLIPPING MODE opcode 0313 0216
313 216
MARKER CLIPPING MODE opcode 0313
313 217 02/7
EDGE CLIPPING MODE opcode 0313 0218
313 218
NEW REGION opcode 0313 0219
313 219
SAVE PRIMITlVE CONTEXT opcode 2110 0313 02110
2/11
RESTORE PRIMITIVE CONTEXT opcode 313 0313 02/l 1
PROTECTION REGION INDICATOR opcode 313 310 0313 0310
GENERALIZED TEXT PATH MODE opcode 313 311 0313 03/l
MITRE LIMIT opcode 313 312 0313 0312
0313 0313
TRANSPARENT CELL COLOUR opcode 313 313
POLYLINE opcode 0210
2/O
DISJOINT POLYLINE opcode 02/l
POLYMARKER opcode 0212
TEXT opcode 0213
RESTRICTED TEXT opcode 0214
APPEND TEXT opcode 0215
POLYGON opcode 216
POLYGON SET opcode 0217
CELL ARRAY opcode 02/8
m
GENERALIZED DRAWING PRIMITIVE opcode 0219
2110 02110
RECTANGLE opcode
ISO/IEC 8632-2: 1992 (E)
Method of encoding opcodes
Opcode assignments
Opcodes for metafile elements (continued)
Table l-
8-Bit coding
7-Bit coding
3pcode
02/O
314 0314
CIRCLE opcode 210
0314 02/l
CIRCULAR ARC 3 POINT opcode 314 211
0314 0212
CIRCULAR ARC 3 POINT CLOSE opcode 314 212
0314 0213
CIRCULAR ARC CENTRE opcode 314 213
0314 0214
CIRCULAR ARC CENTRE CLOSE opcode 314 214
0314 0215
ELLIPSE opcode 314 215
0314 0216
ELLIPTICAL ARC opcode 314 216
ELLIPTICAL ARC CLOSE opcode 217 0314 0217
CIRCULAR ARC CENTRE REVERSED opcode 218 0314 0218
CONNECTING EDGE opcode 219 0314 0219
HYPERBOLIC ARC opcode 314 2110 02110
PARABOLIC ARC opcode 314 0314 02/l 1
2112 0314 02112
NON-UNIFORM B-SPLINE opcode 314
NON-UNIFORM RATIONAL B-SPLINE opcode 2113 0314 02113
POLYBEZIER opcode 314 0314 02114
2115 0314 02115
POLY SY MBOL opcode 314
0314 0310
BITONAL TILE opcode 314 3/O
. 0314 03/l
TILE opcode 314 311
0315 02/O
LINE BUNDLE INDEX opcode 315 2/O
0315 02/l
LINE TYPE opcode 315 211
0315 0212
LINE WIDTH 315 212
0315 0213
LINE COLOUR opcode 315 213
MARKER BUNDLE INDEX opcode 0315 0214
315 214
MARKER TYPE opcode 0315 0215
315 215
MARKER SIZE opcode 0315 0216
315 216
217 0315 0217
MARKER COLOUR opcode 315
TEXT BUNDLE INDEX opcode 0315 03/O
315 3/O
TEXT FONT INDEX opcode 0315 03/l
315 311
TEXT PRECISION opcode 0315 0312
315 312
CHARACTER EXPANSION FACTOR opcode 0315 0313
315 313
CHARACTER SPACING opcode 0315 0314
315 314
TEXT COLOUR opcode 0315 0315
315 315
CHARACTER HEIGHT opcode 0315 0316
CHARACTER ORIENTATION opcode 0315 0317
TEXT PATH opcode 0315 0318
315 318
TEXT ALIGNMENT opcode 0315 0319
315 319
CHARACTER SET INDEX opcode 3110 0315 03110
ALTERNATE CHARACTER SET INDEX opcode 3/l 1 0315 03/l 1
FILL BUNDLE INDEX opcode
0316 0210
316 2/O
INTERIOR STYLE opcode 0316 02/l
316 211
FILL COLOUR opcode 0316 0212
316 212
HATCH INDEX opcode 03/6 0213
316 213
PATTERN INDEX opcode 0316 0214
316 214
EDGE BUNDLE INDEX opcode 0316 0215
316 215
EDGE TYPE opcode 0316 0216
316 216
EDGE WIDTH opcode 0316 0217
316 217
EDGE COLOUR opcode 0316 0218
316 218
EDGE VISIBILITY opcode 03/6 0219
316 219
FILL REFERENCE POINT opcode 2110 0316 02110
ISO/IEC 8632-2: 1992 (E)
Opcode assignments
Method of encoding opcodes
Table 1 - Opcodes for metafile elements (concluded)
7-Bit coding 8-Bit coding
Opcode
2/l 1 0316 02/l 1
PATTERN TABLE opcode 316
. 2112 0316 02112
PATTERN SIZE opcode 316
0316 03/O
COLOUR TABLE opcode 316 310
0316 03/l
ASPECT SOURCE FLAGS opcode 316 311
PICK IDENTIFIER opcode 316 312 0316 0312
0315 02/s
LINE CAP opcode 315 218
LINE JOIN opcode 0315 0219
315 219
LINE TYPE CONTINUATION opcode 2110 0315 02110
2/l 1
LINE TYPE INITIAL OFFSET opcode 0315 02111
TEXT SCORE TYPE opcode 315 0315 02112
2113 0315
RESTRICTED TEXT TYPE opcode 315 02113
2114 0315 02114
INTERPOLATED INTERIOR opcode 315
2115 0315 02115
EDGE CAP opcode 315
2113 0316 02113
EDGE JOIN opcode 316
2114 0316 02114
EDGE TYPE CONTINUATION opcode 316
EDGE TYPE INITIAL OFFSET opcode 2115 0316 02115
SYMBOL LIBRARY INDEX opcode 0316 0313
316 313
SYMBOL COLOUR opcode 0316 0314
316 314
SYMBOL SIZE opcode 0316 0315
316 315
SYMBOL ORIENTATION opcode 0316 0316
316 316
ESCAPE opcode 0317 02/O
317 210
DOMAIN RING opcode 0317 03/O
317 310
MESSAGE opcode 0317 02/l
317 211
APPLICATION DATA opcode 317 0317 0212
COPY SEGMENT opcode
318 210 0318 02/O
INHERITANCE FILTER opcode 0318 0211
318 211
CLIP INHERITANCE opcode 0318 0212
318 212
SEGMENT TRANSFORMATION opcode 0318 0213
318 213
SEGMENT HIGHLIGHTING opcode 0318 0214
318 214
SEGMENT DISPLAY PRIORITY opcode
0318 0215
318 215
SEGMENT PICK PRIORITY opcode
0318 0216
318 216
NOTE - There is no no-op element in the character encoding. However, the character substitution mechanism
allows generators to achieve this effect.
ISO/IEC 8632-2: 1992 (E)
6 Method of encoding parameters
The parameter part of a CGM element may contain one or more parameters, each parameter consishg of
one or more bytes.
All parameters are coded in columns 4 through 7. (However, the coded representation of a ‘string’ parame-
ter may include bit combinations from other columns of the code table - see the description of string
parameters in 6.9). The general format of a parameter byte is
bl
b8
+-+-+-----------+
IXlllb b b b b bl
+-+-+-----------+
In an 8-bit environment it is 0. Bit
The “X” (bit b8) is the parity bit (or omitted bit) in a 7-bit environment.
b7 is the parameter flag.
Except for ‘string’, ‘string fixed’, and ‘data record’ parameters all parameters are encoded using one or both
of two formats, Basic format or Bitstream format.
6.1 Basic format
Each Basic format parameter is coded as a sequence of one or more bytes, structured as follows:
b8 bl
+-+-+-+-+-------+
IXlllelslb b b bl first byte
+-+-+-+-+-------+
.
bl
b8
+-+-+-+---------+
IXlllelb b b b bl last byte
+-+-+-+--------+
The “X” (bit b8) is the parity bit (or omitted bit) in a 7-bit environment. In an 8-bit environment it is 0. Bit
b7 is the parameter flag.
“e” (b6 of each byte) is the extension flag. For single byte parameters, the extension flag is 0. In multi-byte
parameters, the extension flag is 1 in all bytes except the last byte, where it is 0.
Bits b5 through bl are the data bits of the parameter.
“s” is the sign bit; if equal to 0 then the integer is non-negative and if equal to 1 then the integer is negative.
The number zero shall always be coded as “plus zero” 4/O. The “minus zero” coding is reserved for special
usage (see 6.6.3).
The Basic format is used to encode
enumerated types (E);
a>
colour indices (CI);
b)
colour components (CCO);
C>
indices other than colour indices (IX);
d)
integers (I);
e>
ISO/IEC 8632-2: 1992 (E)
Method of encoding parameters Basic format
real numbers (R);
f)
non-incremental coordinates.
s)
fixed-precision 8-bit unsigned integers - octets (UIS);
l-0
fixed-precision 32-bit unsigned integers (U132).
The most significant part of the parameter is coded in the first byte. The least significant part of the param-
eter is coded in the last byte.
6.2 Bitstream format
Each Bitstream format parameter is encoded as a sequence of one or more bytes, structured as follows:
b8 bl
+-+-+----------+
IXlllb b b b b bl first byte
+-+-+----------+
.
bl
b8
+-+-+-----------+
IXlllb b b b b bl last byte
+-+-+----------+
The “X” is the parity bit (or omitted bit) in a 7-bit environment. In an 8-bit environment it is 0. Bit b7 is
the parameter flag.
Bits b6 through bl are the data bits of the parameter.
The Bitstream format is used to encode:
incremental mode coordinates (see 6.6.2);
a>
colour direct (see 6.8);
b)
colour index lists (see 6.8).
c>
the compressed bitstream (BS) data type (see 6.15).
d)
Bitstream data are packed in consecutive databits starting from high-numbered bits to lower-numbered bits
of the first byte for the most significant part of the bitstream data.
The end of a Bitstream format parameter cannot be derived from the Bitstream format itself (the format is
not self-delimiting). Instead,
-
...