ISO/IEC DIS 8825-3
(Main)Information technology -- ASN.1 encoding rules
Information technology -- ASN.1 encoding rules
Technologies de l'information -- Règles de codage ASN.1
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DRAFT INTERNATIONAL STANDARD
ISO/IEC DIS 8825-3
ISO/IEC JTC 1/SC 6 Secretariat: KATS
Voting begins on: Voting terminates on:
2020-09-28 2020-12-21
Information technology — ASN.1 encoding rules —
Part 3:
Specification of Encoding Control Notation (ECN)
Technologies de l'information — Règles de codage ASN.1 —
Partie 3: Spécification de la notation de contrôle de codage (ECN)
ICS: 35.100.60
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
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STANDARDS MAY ON OCCASION HAVE TO
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POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/IEC DIS 8825-3:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO/IEC 2020
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ISO/IEC DIS 8825-3:2020(E)
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© ISO/IEC 2020
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ii © ISO/IEC 2020 – All rights reserved
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ISO/IEC DIS 8825-3:2020(E)
CONTENTS
Page
Introduction ......................................................................................................................................................................... ix
1 Scope ......................................................................................................................................................................... 1
2 Normative references................................................................................................................................................. 1
2.1 Identical Recommendations | International Standards ................................................................................... 1
2.2 Additional references ..................................................................................................................................... 2
3 Definitions ................................................................................................................................................................. 2
3.1 ASN.1 definitions ........................................................................................................................................... 2
3.2 ECN-specific definitions ................................................................................................................................ 2
4 Abbreviations ............................................................................................................................................................ 5
5 Definition of ECN syntax .......................................................................................................................................... 5
6 Encoding conventions and notation ........................................................................................................................... 5
7 The ECN character set ............................................................................................................................................... 6
8 ECN lexical items ...................................................................................................................................................... 6
8.1 Encoding object references ............................................................................................................................ 6
8.2 Encoding object set references ....................................................................................................................... 7
8.3 Encoding class references .............................................................................................................................. 7
8.4 Reserved word items ...................................................................................................................................... 7
8.5 Reserved encoding class name items ............................................................................................................. 7
8.6 Non-ECN item ............................................................................................................................................... 8
9 ECN Concepts ........................................................................................................................................................... 8
9.1 Encoding Control Notation (ECN) specifications .......................................................................................... 8
9.2 Encoding classes ............................................................................................................................................ 8
9.3 Encoding structures ........................................................................................................................................ 9
9.4 Encoding objects ............................................................................................................................................ 9
9.5 Encoding object sets ..................................................................................................................................... 10
9.6 Defining new encoding classes .................................................................................................................... 10
9.7 Defining encoding objects ............................................................................................................................ 11
9.8 Differential encoding-decoding .................................................................................................................... 12
9.9 Encoders options in encodings ..................................................................................................................... 12
9.10 Properties of encoding objects ..................................................................................................................... 12
9.11 Parameterization ........................................................................................................................................... 13
9.12 Governors ..................................................................................................................................................... 13
9.13 General aspects of encodings ....................................................................................................................... 13
9.14 Identification of information elements ......................................................................................................... 14
9.15 Reference fields and determinants ............................................................................................................... 14
9.16 Replacement classes and structures .............................................................................................................. 14
9.17 Mapping abstract values onto fields of encoding structures ......................................................................... 15
9.18 Transforms and transform composites ......................................................................................................... 16
9.19 Contents of Encoding Definition Modules ................................................................................................... 17
9.20 Contents of the Encoding Link Module ....................................................................................................... 17
9.21 Defining encodings for primitive encoding classes ...................................................................................... 17
9.22 Application of encodings ............................................................................................................................. 19
9.23 Combined encoding object set ..................................................................................................................... 19
9.24 Application point .......................................................................................................................................... 20
9.25 Conditional encodings .................................................................................................................................. 20
9.26 Other conditions for applying encodings ..................................................................................................... 21
9.27 Encoding control for the open type .............................................................................................................. 21
9.28 Changes to ASN.1 Recommendations | International Standards .................................................................. 21
10 Identifying encoding classes, encoding objects, and encoding object sets .............................................................. 22
Rec. ITU-T X.692 (08/2015) iii© ISO/IEC 2020 – All rights reserved
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ISO/IEC DIS 8825-3:2020(E)
11 Encoding ASN.1 types ............................................................................................................................................ 24
11.1 General ......................................................................................................................................................... 24
11.2 Built-in encoding classes used for implicitly generated encoding structures ............................................... 25
11.3 Simplification and expansion of ASN.1 notation for encoding purposes ..................................................... 26
11.4 The implicitly generated encoding structure ................................................................................................ 27
12 The Encoding Link Module (ELM) ......................................................................................................................... 28
12.1 Structure of the ELM.................................................................................................................................... 28
12.2 Encoding types ............................................................................................................................................. 29
13 Application of encodings ......................................................................................................................................... 29
13.1 General ......................................................................................................................................................... 29
13.2 The combined encoding object set and its application ................................................................................. 30
14 The Encoding Definition Module (EDM) ............................................................................................................... 32
15 The renames clause.................................................................................................................................................. 33
15.1 Explicitly generated and exported structures ............................................................................................... 33
15.2 Name changes .............................................................................................................................................. 35
15.3 Specifying the region for name changes ...................................................................................................... 36
16 Encoding class assignments .................................................................................................................................... 36
16.1 General ......................................................................................................................................................... 36
16.2 Encoding structure definition ....................................................................................................................... 39
16.3 Alternative encoding structure ..................................................................................................................... 41
16.4 Repetition encoding structure ....................................................................................................................... 42
16.5 Concatenation encoding structure ................................................................................................................ 42
17 Encoding object assignments................................................................................................................................... 43
17.1 General ......................................................................................................................................................... 43
17.2 Encoding with a defined syntax ................................................................................................................... 44
17.3 Encoding with encoding object sets ............................................................................................................. 45
17.4 Encoding using value mappings ................................................................................................................... 45
17.5 Encoding an encoding structure ................................................................................................................... 46
17.6 Differential encoding-decoding .................................................................................................................... 48
17.7 Encoding options .......................................................................................................................................... 48
17.8 Non-ECN definition of encoding objects ..................................................................................................... 49
18 Encoding object set assignments ............................................................................................................................. 50
18.1 General ......................................................................................................................................................... 50
18.2 Built-in encoding object sets ........................................................................................................................ 50
19 Mapping values ....................................................................................................................................................... 51
19.1 General ......................................................................................................................................................... 51
19.2 Mapping by explicit values .......................................................................................................................... 52
19.3 Mapping by matching fields ......................................................................................................................... 53
19.4 Mapping by #TRANSFORM encoding objects .............................................................................................. 54
19.5 Mapping by abstract value ordering ............................................................................................................. 55
19.6 Mapping by value distribution ..................................................................................................................... 56
19.7 Mapping integer values to bits ..................................................................................................................... 57
20 Defining encoding objects using defined syntax ..................................................................................................... 58
21 Types used in defined syntax specification ............................................................................................................. 59
21.1 The Unit type ............................................................................................................................................. 59
21.2 The EncodingSpaceSize type ............................................................................................................... 59
21.3 The EncodingSpaceDetermination type .......................................................................................... 60
21.4 The UnusedBitsDetermination type ................................................................................................. 61
21.5 The OptionalityDetermination type .............................................................................................. 61
21.6 The AlternativeDetermination type .............................................................................................. 62
21.7 The RepetitionSpaceDetermination type ..................................................................................... 63
21.8 The Justification type ........................................................................................................................ 64
21.9 The Padding type ...................................................................................................................................... 64
iv Rec. ITU-T X.692 (08/2015)© ISO/IEC 2020 – All rights reserved
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ISO/IEC DIS 8825-3:2020(E)
21.10 The Pattern and Non-Null-Pattern types ....................................................................................... 64
21.11 The RangeCondition type ...................................................................................................................... 65
21.12 The Comparison type ............................................................................................................................... 66
21.13 The SizeRangeCondition type ............................................................................................................ 66
21.14 The ReversalSpecification type ..................................................................................................... 67
21.15 The ResultSize type ............................................................................................................................... 67
21.16 The HandleValueSet type ...................................................................................................................... 68
21.17 The IntegerMapping type ..................................................................................................................... 68
22 Commonly used encoding property groups ............................................................................................................. 68
22.1 Replacement specification ............................................................................................................................ 68
22.1.1 Encoding properties, syntax and purpose ................................................................................... 69
22.1.2 Specification restrictions ............................................................................................................ 70
22.1.3 Encoder actions .......................................................................................................................... 71
22.1.4 Decoder actions .......................................................................................................................... 71
22.2 Pre-alignment and padding specification ..................................................................................................... 71
22.2.1 Encoding properties, syntax and purpose ................................................................................... 71
22.2.2 Specification constraints ............................................................................................................ 72
22.2.3 Encoder actions .......................................................................................................................... 72
22.2.4 Decoder actions .......................................................................................................................... 72
22.3 Start pointer specification ............................................................................................................................. 72
22.3.1 Encoding properties, syntax and purpose ................................................................................... 72
22.3.2 Specification constraints ............................................................................................................ 73
22.3.3 Encoder actions .......................................................................................................................... 73
22.3.4 Decoder actions .......................................................................................................................... 73
22.4 Encoding space specification ....................................................................................................................... 73
22.4.1 Encoding properties, syntax and purpose ................................................................................... 73
22.4.2 Specification restrictions ............................................................................................................ 74
22.4.3 Encoder actions .......................................................................................................................... 75
22.4.4 Decoder actions .......................................................................................................................... 75
22.5 Optionality determination ............................................................................................................................ 75
22.5.1 Encoding properties, syntax and purpose ................................................................................... 75
22.5.2 Specification restrictions ............................................................................................................ 76
22.5.3 Encoder actions .......................................................................................................................... 77
22.5.4 Decoder actions .......................................................................................................................... 77
22.6 Alternative determination ............................................................................................................................. 77
22.6.1 Encoding properties, syntax and purpose ................................................................................... 77
22.6.2 Specification restrictions ............................................................................................................ 78
22.6.3 Encoder actions .......................................................................................................................... 78
22.6.4 Decoder actions .......................................................................................................................... 79
22.7 Repetition space specification ...................................................................................................................... 79
22.7.1 Encoding properties, syntax and purpose ................................................................................... 79
22.7.2 Specification constraints ............................................................................................................ 80
22.7.3 Encoder actions .......................................................................................................................... 81
22.7.4 Decoder actions .......................................................................................................................... 81
22.8 Value padding and justification .................................................................................................................... 82
22.8.1 Encoding properties, syntax, and purpose .................................................................................. 82
22.8.2 Specification restrictions ............................................................................................................ 83
22.8.3 Encoder actions .......................................................................................................................... 83
22.8.4 Decoder actions .......................................................................................................................... 84
22.9 Identification handle specification ............................................................................................................... 84
22.9.1 Encoding properties, syntax and purpose ................................................................................... 84
22.9.2 Specification constraints ............................................................................................................ 85
22.9.3 Encoders actions ......................................................................................................................... 85
22.9.4 Decoders actions ........................................................................................................................ 85
22.10 Concatenation specification ......................................................................................................................... 85
22.10.1 Encoding properties, syntax and purpose ................................................................................... 85
22.10.2 Specification constraints ............................................................................................................ 86
22.10.3 Encoder actions .......................................................................................................................... 86
22.10.4 Decoder actions .......................................................................................................................... 86
22.11 Contained type encoding specification ......................................................................................................... 86
Rec. ITU-T X.692 (08/2015) v© ISO/IEC 2020 – All rights reserved
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ISO/IEC DIS 8825-3:2020(E)
22.11.1 Encoding properties, syntax and purpose ................................................................................... 86
22.11.2 Encoder actions .......................................................................................................................... 87
22.11.3 Decoder actions .......................................................................................................................... 87
22.12 Bit reversal specification .............................................................................................................................. 87
22.12.1 Encoding properties, syntax, and purpose .................................................................................. 87
22.12.2 Specification constraints ............................................................................................................ 87
22.12.3 Encoder actions .......................................................................................................................... 88
22.12.4 Decoder actions .......................................................................................................................... 88
23 Defined syntax specification for bit-field and constructor classes .......................................................................... 88
23.1 Defining encoding objects for classes in the alternatives category .............................................................. 88
23.1.1 The defined syntax ..................................................................................................................... 88
23.1.2 Purpose and restrictions ............................................................................................................. 89
23.1.3 Encoder actions .......................................................................................................................... 89
23.1.4 Decoder actions .......................................................................................................................... 89
23.2 Defining encoding objects for classes in the bitstring category ................................................................... 89
23.2.1 The defined syntax ..................................................................................................................... 89
23.2.2 Model for the...
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