Programming languages — Guidance to avoiding vulnerabilities in programming languages — Part 3: C

This document specifies software programming language vulnerabilities to be avoided in the development of systems where assured behaviour is required for security, safety, mission-critical and business-critical software. In general, this guidance is applicable to the software developed, reviewed, or maintained for any application. This document describes the way that the vulnerabilities listed in ISO/IEC TR 24772-1 are manifested or avoided in the C language.

Langages de programmation — Conduite pour éviter les vulnérabilités dans les langages de programmation — Partie 3: C

General Information

Status
Published
Publication Date
19-May-2020
Current Stage
6060 - International Standard published
Start Date
22-Apr-2020
Completion Date
20-May-2020
Ref Project

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TECHNICAL ISO/IEC TR
REPORT 24772-3
First edition
2020-05
Programming languages — Guidance
to avoiding vulnerabilities in
programming languages —
Part 3:
Langages de programmation — Conduite pour éviter les
vulnérabilités dans les langages de programmation —
Partie 3: C
Reference number
ISO/IEC TR 24772-3:2020(E)
ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC TR 24772-3:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC TR 24772-3:2020(E)
Contents Page

Foreword ......................................................................................................................................................................................................................................vii

Introduction ............................................................................................................................................................................................................................viii

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Language concepts ............................................................................................................................................................................................. 2

5 Avoiding programming language vulnerabilities in C ................................................................................................... 2

6 Specific guidance for C vulnerabilities .......................................................................................................................................... 3

6.1 General ........................................................................................................................................................................................................... 3

6.2 Type system [IHN] ............................................................................................................................................................................... 4

6.2.1 Applicability to language .......................................................................................................................................... 4

6.2.2 Guidance to language users .................................................................................................................................... 5

6.3 Bit representations [STR] .............................................................................................................................................................. 5

6.3.1 Applicability to language .......................................................................................................................................... 5

6.3.2 Guidance to language users .................................................................................................................................... 5

6.4 Floating-point arithmetic [PLF] ............................................................................................................................................... 6

6.4.1 Applicability to language .......................................................................................................................................... 6

6.4.2 Guidance to language users .................................................................................................................................... 6

6.5 Enumerator issues [CCB] ............................................................................................................................................................... 6

6.5.1 Applicability to language .......................................................................................................................................... 6

6.5.2 Guidance to language users .................................................................................................................................... 7

6.6 Conversion errors [FLC] .................................................................................................................................................................. 8

6.6.1 Applicability to language .......................................................................................................................................... 8

6.6.2 Guidance to language users .................................................................................................................................... 9

6.7 String termination [CJM] .............................................................................................................................................................10

6.7.1 Applicability to language .......................................................................................................................................10

6.7.2 Guidance to language users .................................................................................................................................10

6.8 Buffer boundary violation (buffer overflow) [HCB] ............................................................................................10

6.8.1 Applicability to language .......................................................................................................................................10

6.8.2 Guidance to language users .................................................................................................................................11

6.9 Unchecked array indexing [XYZ] ..........................................................................................................................................11

6.9.1 Applicability to language .......................................................................................................................................11

6.9.2 Guidance to language users .................................................................................................................................12

6.10 Unchecked array copying [XYW] ..........................................................................................................................................12

6.10.1 Applicability to language .......................................................................................................................................12

6.10.2 Guidance to language users .................................................................................................................................12

6.11 Pointer type conversions [HFC] ............................................................................................................................................13

6.11.1 Applicability to language .......................................................................................................................................13

6.11.2 Guidance to language users .................................................................................................................................13

6.12 Pointer arithmetic [RVG] .............................................................................................................................................................13

6.12.1 Applicability to language .......................................................................................................................................13

6.12.2 Guidance to language users .................................................................................................................................14

6.13 Null pointer dereference [XYH] .............................................................................................................................................14

6.13.1 Applicability to language .......................................................................................................................................14

6.13.2 Guidance to language users .................................................................................................................................14

6.14 Dangling reference to heap [XYK] .......................................................................................................................................15

6.14.1 Applicability to language .......................................................................................................................................15

6.14.2 Guidance to language users .................................................................................................................................15

6.15 Arithmetic wrap-around error [FIF] .................................................................................................................................16

6.15.1 Applicability to language .......................................................................................................................................16

6.15.2 Guidance to language users .................................................................................................................................16

6.16 Using shift operations for multiplication and division [PIK] .......................................................................17

© ISO/IEC 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/IEC TR 24772-3:2020(E)

6.16.1 Applicability to language .......................................................................................................................................17

6.16.2 Guidance to language users .................................................................................................................................17

6.17 Choice of clear names [NAI]......................................................................................................................................................17

6.17.1 Applicability to language .......................................................................................................................................17

6.17.2 Guidance to language users .................................................................................................................................17

6.18 Dead store [WXQ] ..............................................................................................................................................................................18

6.18.1 Applicability to language .......................................................................................................................................18

6.18.2 Guidance to language users .................................................................................................................................18

6.19 Unused variable [YZS] ...................................................................................................................................................................18

6.19.1 Applicability to language .......................................................................................................................................18

6.19.2 Guidance to language users .................................................................................................................................18

6.20 Identifier name reuse [YOW] ...................................................................................................................................................18

6.20.1 Applicability to language .......................................................................................................................................18

6.20.2 Guidance to language users .................................................................................................................................19

6.21 Namespace issues [BJL]................................................................................................................................................................19

6.21.1 Applicability to language .......................................................................................................................................19

6.22 Initialization of variables [LAV] .............................................................................................................................................19

6.22.1 Applicability to language .......................................................................................................................................19

6.22.2 Guidance to language users .................................................................................................................................19

6.23 Operator precedence and associativity [JCW] ..........................................................................................................19

6.23.1 Applicability to language .......................................................................................................................................19

6.23.2 Guidance to language users .................................................................................................................................20

6.24 Side-effects and order of evaluation of operands [SAM] .................................................................................20

6.24.1 Applicability to language .......................................................................................................................................20

6.24.2 Guidance to language users .................................................................................................................................20

6.25 Likely incorrect expression [KOA] .......................................................................................................................................21

6.25.1 Applicability to language .......................................................................................................................................21

6.25.2 Guidance to language users .................................................................................................................................21

6.26 Dead and deactivated code [XYQ] ........................................................................................................................................22

6.26.1 Applicability to language .......................................................................................................................................22

6.26.2 Guidance to language users .................................................................................................................................22

6.27 Switch statements and static analysis [CLL] ..............................................................................................................22

6.27.1 Applicability to language .......................................................................................................................................22

6.27.2 Guidance to language users .................................................................................................................................23

6.28 Demarcation of control flow [EOJ] ......................................................................................................................................23

6.28.1 Applicability to language .......................................................................................................................................23

6.28.2 Guidance to language users .................................................................................................................................23

6.29 Loop control variables [TEX] ...................................................................................................................................................24

6.29.1 Applicability to language .......................................................................................................................................24

6.29.2 Guidance to language users .................................................................................................................................24

6.30 Off-by-one error [XZH] ..................................................................................................................................................................25

6.30.1 Applicability to language .......................................................................................................................................25

6.30.2 Guidance to language users .................................................................................................................................25

6.31 Unstructured programming [EWD] ...................................................................................................................................25

6.31.1 Applicability to language .......................................................................................................................................25

6.31.2 Guidance to language users .................................................................................................................................25

6.32 Passing parameters and return values [CSJ] ..............................................................................................................26

6.32.1 Applicability to language .......................................................................................................................................26

6.32.2 Guidance to language users .................................................................................................................................26

6.33 Dangling references to stack frames [DCM] ................................................................................................................27

6.33.1 Applicability to language .......................................................................................................................................27

6.33.2 Guidance to language users .................................................................................................................................27

6.34 Subprogram signature mismatch [OTR] ........................................................................................................................27

6.34.1 Applicability to language .......................................................................................................................................27

6.34.2 Guidance to language users .................................................................................................................................28

6.35 Recursion [GDL] ..................................................................................................................................................................................28

6.35.1 Applicability to language .......................................................................................................................................28

6.35.2 Guidance to language users .................................................................................................................................28

iv © ISO/IEC 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/IEC TR 24772-3:2020(E)

6.36 Ignored error status and unhandled exceptions [OYB] ....................................................................................28

6.36.1 Applicability to language .......................................................................................................................................28

6.36.2 Guidance to language users .................................................................................................................................28

6.37 Type-breaking reinterpretation of data [AMV] ........................................................................................................29

6.37.1 Applicability to language .......................................................................................................................................29

6.37.2 Guidance to language users .................................................................................................................................29

6.38 Deep vs. shallow copying [YAN] ............................................................................................................................................29

6.38.1 Applicability to language .......................................................................................................................................29

6.38.2 Guidance to language users .................................................................................................................................29

6.39 Memory leaks and heap fragmentation [XYL] ..........................................................................................................30

6.39.1 Applicability to language .......................................................................................................................................30

6.39.2 Guidance to language users .................................................................................................................................30

6.40 Templates and generics [SYM] ...............................................................................................................................................30

6.41 Inheritance [RIP] ................................................................................................................................................................................30

6.42 Violations of the Liskov substitution principle or the contract model [BLP] ................................30

6.43 Redispatching [PPH] .......................................................................................................................................................................30

6.44 Polymorphic variables [BKK] ..................................................................................................................................................30

6.45 Extra intrinsics [LRM] ....................................................................................................................................................................30

6.46 Argument passing to library functions [TRJ] .............................................................................................................30

6.46.1 Applicability to language .......................................................................................................................................30

6.46.2 Guidance to language users .................................................................................................................................31

6.47 Inter-language calling [DJS] ......................................................................................................................................................31

6.47.1 Applicability to language .......................................................................................................................................31

6.47.2 Guidance to language users .................................................................................................................................31

6.48 Dynamically linked code and self-modifying code [NYY] ...............................................................................31

6.48.1 Applicability to language .......................................................................................................................................31

6.48.2 Guidance to language users .................................................................................................................................32

6.49 Library signature [NSQ] ...............................................................................................................................................................32

6.49.1 Applicability to language .......................................................................................................................................32

6.49.2 Guidance to language users .................................................................................................................................32

6.50 Unanticipated exceptions from library routines [HJW] ....................................................................................32

6.51 Pre-processor directives [NMP] ............................................................................................................................................32

6.51.1 Applicability to language .......................................................................................................................................32

6.51.2 Guidance to language users .................................................................................................................................33

6.52 Suppression of language-defined run-time checking [MXB]........................................................................33

6.53 Provision of inherently unsafe operations [SKL] ...................................................................................................33

6.53.1 Applicability to language .......................................................................................................................................33

6.53.2 Guidance to language users .................................................................................................................................33

6.54 Obscure language features [BRS] .........................................................................................................................................34

6.54.1 Applicability of language .......................................................................................................................................34

6.54.2 Guidance to language users .................................................................................................................................34

6.55 Unspecified behaviour [BQF] ..................................................................................................................................................34

6.55.1 Applicability of language .......................................................................................................................................34

6.55.2 Guidance to language users .................................................................................................................................34

6.56 Undefined behaviour [EWF].....................................................................................................................................................34

6.56.1 Applicability to language .......................................................................................................................................34

6.56.2 Guidance to language users .................................................................................................................................35

6.57 Implementation–defined behaviour [FAB] ..................................................................................................................35

6.57.1 Applicability to language .......................................................................................................................................35

6.57.2 Guidance to language users .................................................................................................................................35

6.58 Deprecated language features [MEM] ..............................................................................................................................36

6.58.1 Applicability to language .......................................................................................................................................36

6.58.2 Guidance to language users .................................................................................................................................36

6.59 Concurrency — Activation [CGA] .........................................................................................................................................36

6.59.1 Applicability to language ..........................................................................................................

...

TECHNICAL ISO/IEC TR
REPORT 24772-3
First edition
Programming languages — Guidance
to avoiding vulnerabilities in
programming languages —
Part 3:
Langages de programmation — Conduite pour éviter les
vulnérabilités dans les langages de programmation —
Partie 3: C
PROOF/ÉPREUVE
Reference number
ISO/IEC TR 24772-3:2020(E)
ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC TR 24772-3:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO/IEC 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC TR 24772-3:2020(E)
Contents Page

Foreword ......................................................................................................................................................................................................................................vii

Introduction ............................................................................................................................................................................................................................viii

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Language concepts ............................................................................................................................................................................................. 2

5 Avoiding programming language vulnerabilities in C ................................................................................................... 2

6 Specific guidance for C vulnerabilities .......................................................................................................................................... 3

6.1 General ........................................................................................................................................................................................................... 3

6.2 Type system [IHN] ............................................................................................................................................................................... 4

6.2.1 Applicability to language .......................................................................................................................................... 4

6.2.2 Guidance to language users .................................................................................................................................... 5

6.3 Bit representations [STR] .............................................................................................................................................................. 5

6.3.1 Applicability to language .......................................................................................................................................... 5

6.3.2 Guidance to language users .................................................................................................................................... 5

6.4 Floating-point arithmetic [PLF] ............................................................................................................................................... 6

6.4.1 Applicability to language .......................................................................................................................................... 6

6.4.2 Guidance to language users .................................................................................................................................... 6

6.5 Enumerator issues [CCB] ............................................................................................................................................................... 6

6.5.1 Applicability to language .......................................................................................................................................... 6

6.5.2 Guidance to language users .................................................................................................................................... 7

6.6 Conversion errors [FLC] .................................................................................................................................................................. 8

6.6.1 Applicability to language .......................................................................................................................................... 8

6.6.2 Guidance to language users .................................................................................................................................... 9

6.7 String termination [CJM] .............................................................................................................................................................10

6.7.1 Applicability to language .......................................................................................................................................10

6.7.2 Guidance to language users .................................................................................................................................10

6.8 Buffer boundary violation (buffer overflow) [HCB] ............................................................................................10

6.8.1 Applicability to language .......................................................................................................................................10

6.8.2 Guidance to language users .................................................................................................................................11

6.9 Unchecked array indexing [XYZ] ..........................................................................................................................................11

6.9.1 Applicability to language .......................................................................................................................................11

6.9.2 Guidance to language users .................................................................................................................................12

6.10 Unchecked array copying [XYW] ..........................................................................................................................................12

6.10.1 Applicability to language .......................................................................................................................................12

6.10.2 Guidance to language users .................................................................................................................................12

6.11 Pointer type conversions [HFC] ............................................................................................................................................13

6.11.1 Applicability to language .......................................................................................................................................13

6.11.2 Guidance to language users .................................................................................................................................13

6.12 Pointer arithmetic [RVG] .............................................................................................................................................................13

6.12.1 Applicability to language .......................................................................................................................................13

6.12.2 Guidance to language users .................................................................................................................................14

6.13 Null pointer dereference [XYH] .............................................................................................................................................14

6.13.1 Applicability to language .......................................................................................................................................14

6.13.2 Guidance to language users .................................................................................................................................14

6.14 Dangling reference to heap [XYK] .......................................................................................................................................15

6.14.1 Applicability to language .......................................................................................................................................15

6.14.2 Guidance to language users .................................................................................................................................15

6.15 Arithmetic wrap-around error [FIF] .................................................................................................................................16

6.15.1 Applicability to language .......................................................................................................................................16

6.15.2 Guidance to language users .................................................................................................................................16

6.16 Using shift operations for multiplication and division [PIK] .......................................................................17

© ISO/IEC 2020 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/IEC TR 24772-3:2020(E)

6.16.1 Applicability to language .......................................................................................................................................17

6.16.2 Guidance to language users .................................................................................................................................17

6.17 Choice of clear names [NAI]......................................................................................................................................................17

6.17.1 Applicability to language .......................................................................................................................................17

6.17.2 Guidance to language users .................................................................................................................................17

6.18 Dead store [WXQ] ..............................................................................................................................................................................18

6.18.1 Applicability to language .......................................................................................................................................18

6.18.2 Guidance to language users .................................................................................................................................18

6.19 Unused variable [YZS] ...................................................................................................................................................................18

6.19.1 Applicability to language .......................................................................................................................................18

6.19.2 Guidance to language users .................................................................................................................................18

6.20 Identifier name reuse [YOW] ...................................................................................................................................................18

6.20.1 Applicability to language .......................................................................................................................................18

6.20.2 Guidance to language users .................................................................................................................................19

6.21 Namespace issues [BJL]................................................................................................................................................................19

6.21.1 Applicability to language .......................................................................................................................................19

6.22 Initialization of variables [LAV] .............................................................................................................................................19

6.22.1 Applicability to language .......................................................................................................................................19

6.22.2 Guidance to language users .................................................................................................................................19

6.23 Operator precedence and associativity [JCW] ..........................................................................................................19

6.23.1 Applicability to language .......................................................................................................................................19

6.23.2 Guidance to language users .................................................................................................................................20

6.24 Side-effects and order of evaluation of operands [SAM] .................................................................................20

6.24.1 Applicability to language .......................................................................................................................................20

6.24.2 Guidance to language users .................................................................................................................................20

6.25 Likely incorrect expression [KOA] .......................................................................................................................................21

6.25.1 Applicability to language .......................................................................................................................................21

6.25.2 Guidance to language users .................................................................................................................................21

6.26 Dead and deactivated code [XYQ] ........................................................................................................................................22

6.26.1 Applicability to language .......................................................................................................................................22

6.26.2 Guidance to language users .................................................................................................................................22

6.27 Switch statements and static analysis [CLL] ..............................................................................................................22

6.27.1 Applicability to language .......................................................................................................................................22

6.27.2 Guidance to language users .................................................................................................................................23

6.28 Demarcation of control flow [EOJ] ......................................................................................................................................23

6.28.1 Applicability to language .......................................................................................................................................23

6.28.2 Guidance to language users .................................................................................................................................23

6.29 Loop control variables [TEX] ...................................................................................................................................................24

6.29.1 Applicability to language .......................................................................................................................................24

6.29.2 Guidance to language users .................................................................................................................................24

6.30 Off-by-one error [XZH] ..................................................................................................................................................................25

6.30.1 Applicability to language .......................................................................................................................................25

6.30.2 Guidance to language users .................................................................................................................................25

6.31 Unstructured programming [EWD] ...................................................................................................................................25

6.31.1 Applicability to language .......................................................................................................................................25

6.31.2 Guidance to language users .................................................................................................................................25

6.32 Passing parameters and return values [CSJ] ..............................................................................................................26

6.32.1 Applicability to language .......................................................................................................................................26

6.32.2 Guidance to language users .................................................................................................................................26

6.33 Dangling references to stack frames [DCM] ................................................................................................................27

6.33.1 Applicability to language .......................................................................................................................................27

6.33.2 Guidance to language users .................................................................................................................................27

6.34 Subprogram signature mismatch [OTR] ........................................................................................................................27

6.34.1 Applicability to language .......................................................................................................................................27

6.34.2 Guidance to language users .................................................................................................................................28

6.35 Recursion [GDL] ..................................................................................................................................................................................28

6.35.1 Applicability to language .......................................................................................................................................28

6.35.2 Guidance to language users .................................................................................................................................28

iv PROOF/ÉPREUVE © ISO/IEC 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/IEC TR 24772-3:2020(E)

6.36 Ignored error status and unhandled exceptions [OYB] ....................................................................................28

6.36.1 Applicability to language .......................................................................................................................................28

6.36.2 Guidance to language users .................................................................................................................................28

6.37 Type-breaking reinterpretation of data [AMV] ........................................................................................................29

6.37.1 Applicability to language .......................................................................................................................................29

6.37.2 Guidance to language users .................................................................................................................................29

6.38 Deep vs. shallow copying [YAN] ............................................................................................................................................29

6.38.1 Applicability to language .......................................................................................................................................29

6.38.2 Guidance to language users .................................................................................................................................29

6.39 Memory leaks and heap fragmentation [XYL] ..........................................................................................................30

6.39.1 Applicability to language .......................................................................................................................................30

6.39.2 Guidance to language users .................................................................................................................................30

6.40 Templates and generics [SYM] ...............................................................................................................................................30

6.41 Inheritance [RIP] ................................................................................................................................................................................30

6.42 Violations of the Liskov substitution principle or the contract model [BLP] ................................30

6.43 Redispatching [PPH] .......................................................................................................................................................................30

6.44 Polymorphic variables [BKK] ..................................................................................................................................................30

6.45 Extra intrinsics [LRM] ....................................................................................................................................................................30

6.46 Argument passing to library functions [TRJ] .............................................................................................................30

6.46.1 Applicability to language .......................................................................................................................................30

6.46.2 Guidance to language users .................................................................................................................................31

6.47 Inter-language calling [DJS] ......................................................................................................................................................31

6.47.1 Applicability to language .......................................................................................................................................31

6.47.2 Guidance to language users .................................................................................................................................31

6.48 Dynamically linked code and self-modifying code [NYY] ...............................................................................31

6.48.1 Applicability to language .......................................................................................................................................31

6.48.2 Guidance to language users .................................................................................................................................32

6.49 Library signature [NSQ] ...............................................................................................................................................................32

6.49.1 Applicability to language .......................................................................................................................................32

6.49.2 Guidance to language users .................................................................................................................................32

6.50 Unanticipated exceptions from library routines [HJW] ....................................................................................32

6.51 Pre-processor directives [NMP] ............................................................................................................................................32

6.51.1 Applicability to language .......................................................................................................................................32

6.51.2 Guidance to language users .................................................................................................................................33

6.52 Suppression of language-defined run-time checking [MXB]........................................................................33

6.53 Provision of inherently unsafe operations [SKL] ...................................................................................................33

6.53.1 Applicability to language .......................................................................................................................................33

6.53.2 Guidance to language users .................................................................................................................................33

6.54 Obscure language features [BRS] .........................................................................................................................................34

6.54.1 Applicability of language .......................................................................................................................................34

6.54.2 Guidance to language users .................................................................................................................................34

6.55 Unspecified behaviour [BQF] ..................................................................................................................................................34

6.55.1 Applicability of language .......................................................................................................................................34

6.55.2 Guidance to language users .................................................................................................................................34

6.56 Undefined behaviour [EWF].....................................................................................................................................................34

6.56.1 Applicability to language .......................................................................................................................................34

6.56.2 Guidance to language users .................................................................................................................................35

6.57 Implementation–defined behaviour [FAB] ..................................................................................................................35

6.57.1 Applicability to language .......................................................................................................................................35

6.57.2 Guidance to language users .................................................................................................................................35

6.58 Deprecated language features [MEM] ..............................................................................................................................36

6.58.1 Applicability to language .......................................................................................................................................36

6.58.2 Guidance to language users .................................................................................................................................36

6.59 Concurrency — Activation [CGA] .........................................................................................................................................36

6.59.1 Applicability to language .............................................................

...

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