Digital audio interface - Part 1: General (IEC 60958-1:2008)

This part of IEC 60958 describes a serial, uni-directional, self-clocking interface for the interconnection of digital audio equipment for consumer and professional applications. It provides the basic structure of the interface. Separate documents define items specific to particular applications. The interface is primarily intended to carry monophonic or stereophonic programmes, encoded using linear PCM and with a resolution of up to 24 bits per sample. When used for other purposes, the interface is able to carry audio data coded other than as linear PCM coded audio samples. Provision is also made to allow the interface to carry data related to computer software or signals coded using non-linear PCM. The format specification for these applications is not part of this standard. The interface is intended for operation at audio sampling fre.

Digitalton-Schnittstelle - Teil 1: Allgemeines (IEC 60958-1:2008)

Interface audionumérique - Partie 1: Généralités (CEI 60958-1:2008)

Digitalni zvokovni vmesnik - 1. del: Splošno (IEC 60958-1:2008)

General Information

Status
Published
Publication Date
21-Oct-2008
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
22-Oct-2008
Due Date
27-Dec-2008
Completion Date
22-Oct-2008

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SLOVENSKI STANDARD
SIST EN 60958-1:2008
01-december-2008
1DGRPHãþD
SIST EN 60958-1:2006
Digitalni zvokovni vmesnik - 1. del: Splošno (IEC 60958-1:2008)
Digital audio interface - Part 1: General (IEC 60958-1:2008)
Digitalton-Schnittstelle - Teil 1: Allgemeines (IEC 60958-1:2008)
Interface audionumérique - Partie 1: Généralités (CEI 60958-1:2008)
Ta slovenski standard je istoveten z: EN 60958-1:2008
ICS:
33.160.30 Avdio sistemi Audio systems
35.200 Vmesniška in povezovalna Interface and interconnection
oprema equipment
SIST EN 60958-1:2008 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60958-1:2008
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SIST EN 60958-1:2008
EUROPEAN STANDARD
EN 60958-1
NORME EUROPÉENNE
October 2008
EUROPÄISCHE NORM
ICS 33.160.01 Supersedes EN 60958-1:2004
English version
Digital audio interface -
Part 1: General
(IEC 60958-1:2008)
Interface audionumérique - Digitalton-Schnittstelle -
Partie 1: Généralités Teil 1: Allgemeines
(CEI 60958-1:2008) (IEC 60958-1:2008)

This European Standard was approved by CENELEC on 2008-10-01. CENELEC members are bound to comply

with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard

the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on

application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CENELEC member into its own language and notified

to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the

Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60958-1:2008 E
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SIST EN 60958-1:2008
EN 60958-1:2008 - 2 -
Foreword

The text of document 100/1252/CDV, future edition 3 of IEC 60958-1, prepared by IEC TC 100, Audio,

video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and was

approved by CENELEC as EN 60958-1 on 2008-10-01.
This European Standard supersedes EN 60958-1:2004.
It includes the following significant changes with respect to EN 60958-1:2004:

Electrical and optical requirements are removed from EN 60958-3; they are specified in EN 60958-1.

The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2009-07-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2011-10-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 60958-1:2008 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60793-2 NOTE Harmonized as EN 60793-2:2008 (not modified).
IEC 60794-2 NOTE Harmonized as EN 60794-2:2003 (not modified).
IEC 60874-1 NOTE Harmonized as EN 60874-1:2007 (not modified).
IEC 60958 NOTE Harmonized in EN 60958 series (not modified).
IEC 61883-6 NOTE Harmonized as EN 61883-6:2005 (not modified).
IEC 61937-1 NOTE Harmonized as EN 61937-1:2007 (not modified).
IEC 61937-2 NOTE Harmonized as EN 61937-2:2007 (not modified).
IEC 61937-3 NOTE Harmonized as EN 61937-3:2003 (not modified).
IEC 61937-4 NOTE Harmonized as EN 61937-4:2003 (not modified).
IEC 61937-5 NOTE Harmonized as EN 61937-5:2006 (not modified).
IEC 61937-6 NOTE Harmonized as EN 61937-6:2006 (not modified).
IEC 61937-7 NOTE Harmonized as EN 61937-7:2005 (not modified).
IEC 61937-8 NOTE Harmonized as EN 61937-8:2007 (not modified).
IEC 61937-9 NOTE Harmonized as EN 61937-9:2007 (not modified).
IEC 62105 NOTE Harmonized as EN 62105:2002 (not modified).
__________
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SIST EN 60958-1:2008
- 3 - EN 60958-1:2008
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60268-11 - Sound system equipment - HD 483.11 S3 1993
Part 11: Application of connectors for the
interconnection of sound system components
1) 2)
IEC 60874-17 - Connectors for optical fibres and cables - EN 60874-17 1997
Part 17: Sectional specification for fibre optic
connector - Type F-05 (friction lock)
1) 2)
IEC 60958-3 - Digital audio interface - EN 60958-3 2006
Part 3: Consumer applications
1) 2)
IEC 60958-4 - Digital audio interface - EN 60958-4 2003
Part 4: Professional applications
Undated reference.
Valid edition at date of issue.
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SIST EN 60958-1:2008
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SIST EN 60958-1:2008
IEC 60958-1
Edition 3.0 2008-09
INTERNATIONAL
STANDARD
Digital audio interface –
Part 1: General
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 33.160.01 ISBN 2-8318-1000-4
® Registered trademark of the International Electrotechnical Commission
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SIST EN 60958-1:2008
– 2 – 60958-1 © IEC:2008(E)
CONTENTS

FOREWORD...........................................................................................................................4

1 Scope...............................................................................................................................6

2 Normative references .......................................................................................................6

3 Terms and definitions .......................................................................................................6

4 Interface format ................................................................................................................8

4.1 Structure of format ..................................................................................................8

4.1.1 Sub-frame format.........................................................................................8

4.1.2 Frame format...............................................................................................9

4.2 Channel coding .......................................................................................................9

4.3 Preambles .............................................................................................................10

4.4 Validity bit .............................................................................................................11

5 Channel status ...............................................................................................................11

5.1 General .................................................................................................................11

5.2 Applications...........................................................................................................11

5.3 General assignment of the first and second channel status bits.............................12

5.4 Category code.......................................................................................................12

6 User data .......................................................................................................................14

6.1 General .................................................................................................................14

6.2 Applications...........................................................................................................14

6.2.1 Professional use........................................................................................14

6.2.2 Consumer use ...........................................................................................14

7 Electrical requirement.....................................................................................................14

7.1 Consumer application............................................................................................14

7.1.1 General .....................................................................................................14

7.1.2 Timing accuracy ........................................................................................14

7.1.3 Unbalanced line.........................................................................................15

7.2 Professional application ........................................................................................18

8 Optical requirements ......................................................................................................18

8.1 Consumer application............................................................................................18

8.1.1 Optical specification ..................................................................................18

8.1.2 Optical connector ......................................................................................19

8.2 Professional applications.......................................................................................19

Annex A (informative) The use of the validity bit ..................................................................20

Annex B (informative) Application documents and specifications..........................................21

Annex C (informative) A relationship of the IEC 60958 series families..................................22

Annex D (informative) Transmission of CD data other than linear PCM audio ......................23

Annex E (informative) The IEC 60958 series conformant data format...................................24

Annex F (informative) Stream change ..................................................................................25

Annex G (informative) Characteristics of optical connection.................................................27

Bibliography..........................................................................................................................29

Figure 1 – Sub-frame format (linear PCM application).............................................................9

Figure 2 – Frame format .........................................................................................................9

Figure 3 – Channel coding ....................................................................................................10

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60958-1 © IEC:2008(E) – 3 –

Figure 4 – Preamble M (shown as 11100010) .......................................................................11

Figure 5 – Simplified example of the configuration of the circuit (unbalanced).......................15

Figure 6 – Rise and fall times ...............................................................................................16

Figure 7 – Intrinsic jitter measurement filter ..........................................................................16

Figure 8 – Eye diagram.........................................................................................................17

Figure 9 – Receiver jitter tolerance template.........................................................................17

Figure 10 – Basic optical connection.....................................................................................18

Figure C.1 – A relationship of IEC 60958 families .................................................................22

Figure F.1 – Audio sources and AV receiver model...............................................................25

Figure F.2 – Switching from linear PCM to non linear PCM ...................................................26

Figure F.3 – Switching from non linear PCM to linear PCM ...................................................26

Figure F.4 – Switching from non-linear PCM to non-linear PCM ............................................26

Table 1 – Preamble coding ...................................................................................................10

Table 2 – Channel status data format ...................................................................................13

Table B.1 – Application documents and specifications ..........................................................21

Table G.1 – Characteristics of standard optical connection (optical interface) .......................27

Table G.2 – Characteristics of optical transmitter (optical interface)......................................27

Table G.3 – Characteristics of optical receiver (optical interface) ..........................................28

Table G.4 – Characteristics of fibre optic cable.....................................................................28

Table G.5 – Optical power budget for the link with plastic fibre .............................................28

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIGITAL AUDIO INTERFACE –
Part 1: General
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard 60958-1 has been prepared by IEC technical committee 100: Audio,

video and multimedia systems and equipment.

This third edition of IEC 60958-1 cancels and replaces the second edition published in 2004

and constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition.

Electrical and optical requirements are removed from IEC 60958-3; they are specified in

IEC 60958-1.
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SIST EN 60958-1:2008
60958-1 © IEC:2008(E) – 5 –
The text of this standard is based on the following documents:
CDV Report on voting
100/1252/CDV 100/1337/RVC

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts of the IEC 60958 series, under the general title Digital audio interface, can

be found on the IEC website.

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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SIST EN 60958-1:2008
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DIGITAL AUDIO INTERFACE –
Part 1: General
1 Scope

This part of IEC 60958 describes a serial, uni-directional, self-clocking interface for the

interconnection of digital audio equipment for consumer and professional applications.

It provides the basic structure of the interface. Separate documents define items specific to

particular applications.

The interface is primarily intended to carry monophonic or stereophonic programmes,

encoded using linear PCM and with a resolution of up to 24 bits per sample.

When used for other purposes, the interface is able to carry audio data coded other than as

linear PCM coded audio samples. Provision is also made to allow the interface to carry data

related to computer software or signals coded using non-linear PCM. The format specification

for these applications is not part of this standard.

The interface is intended for operation at audio sampling frequencies of 32kHz and above.

Auxiliary information is transmitted along with the programme.
2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.

IEC 60268-11, Sound system equipment – Part 11: Application of connectors for the

interconnection of sound system components

IEC 60874-17, Connectors for optical fibres and cables – Part 17: Sectional specification for

fibre optic connector – Type F-05 (friction lock)
IEC 60958-3, Digital audio interface – Part 3: Consumer applications
IEC 60958-4, Digital audio interface – Part 4: Professional applications
3 Terms and definitions

For the purpose of this International Standard, the following terms and definitions apply.

3.1
sampling frequency
frequency of the samples representing an audio signal

NOTE When more than one signal is transmitted through the same interface, the sampling frequencies are

identical.
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SIST EN 60958-1:2008
60958-1 © IEC:2008(E) – 7 –
3.2
audio sample word

value of a digital audio sample; representation is linear in 2's complement binary form

NOTE Positive numbers correspond to positive analogue voltages at the input of the analogue-to-digital converter

(ADC).
3.3
auxiliary sample bit

the four least significant bits (LSBs) which can be assigned as auxiliary sample bits and used

for auxiliary information when the number of audio sample bits in the main data field is less

than or equal to 20
3.4
validity bit

bit indicating whether the main data field bits in the sub-frame (time slots 4 to 27 or 8 to 27,

depending on the audio word length as described in 4.1.1) are reliable or not
3.5
channel status

the channel status carries, in a fixed format, information associated with each main data field

channel which is decodable by any interface user

NOTE Examples of information to be carried in the channel status are: length of audio sample words, pre-

emphasis, sampling frequency, time codes, alphanumeric source and destination codes.

3.6
user data
the user data channel is provided to carry any other information
3.7
parity bit

bit provided to permit the detection of an odd number of errors resulting from malfunctions in

the interface
3.8
preamble
specific patterns used for synchronization
NOTE There are three different preambles (see 4.3).
3.9
sub-frame
fixed structure used to carry information (see 4.1.14.1.1 and 4.1.2)
3.10
frame
sequence of two successive and associated sub-frames
3.11
block
group of 192 consecutive frames

NOTE The start of a block is designated by a special sub-frame preamble (see 4.3).

3.12
channel coding

coding method by which the binary digits are represented for transmission through the

interface
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SIST EN 60958-1:2008
– 8 – 60958-1 © IEC:2008(E)
3.13
unit interval (UI)
the shortest nominal time interval in the coding scheme
NOTE There are 128 UI in a sample frame.
3.14
interface jitter

deviation in the timing of interface data transitions (zero crossings) when compared with an

ideal clock
3.15
intrinsic jitter

output interface jitter of a device that is either free-running or is synchronized to a jitter-free

reference
3.16
jitter gain

ratio of the amplitude of jitter components at the output to their amplitude at the

synchronization input to the device under test
4 Interface format
4.1 Structure of format
4.1.1 Sub-frame format

Each sub-frame is divided into 32 time slots, numbered from 0 to 31 (see Figure 1).

Time slots 0 to 3 (preambles) carry one of the three permitted preambles (see 4.1.2 and 4.3;

also see Figure 2).

Time slots 4 to 27 (main data field) carry the audio sample word in linear 2's complement

representation. The most significant bit (MSB) is carried by time slot 27.
When a 24-bit coding range is used, the LSB is in time slot 4 (see Figure 1).

When a 20-bit coding range is used, time slots 8 to 27 carry the audio sample word with

the LSB in time slot 8. Time slots 4 to 7 may be used for other applications. Under

these circumstances, the bits in the time slots 4 to 7 are designated auxiliary sample bits (see

Figure 1).

If the source provides fewer bits than the interface allows (either 20 or 24), the unused LSBs

are set to a logical "0".

For a non-linear PCM audio application or a data application the main data field may carry

any other information.

Time slot 28 (validity bit) carries the validity bit associated with the main data field (see 4.4).

Time slot 29 (user data bit) carries 1 bit of the user data channel associated with the main

data field channel transmitted in the same sub-frame. For the applications, refer to the other

parts of IEC 60958.

Time slot 30 (channel status bit) carries 1 bit of the channel status information associated with

the main data field channel transmitted in the same sub-frame. For details refer to the other

parts of IEC 60958.
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60958-1 © IEC:2008(E) – 9 –

Time slot 31 (parity bit) carries a parity bit such that time slots 4 to 31 inclusive carry an even

number of ones and an even number of zeroes (even parity).
NOTE The preambles have even parity as an explicit property.
0 3 4 7 8 27 28 31
Sync M
Aux Audio sample word V U C P
Preamble S
Validity flag
User data
Channel status
Parity bit
IEC 1551/08
Figure 1 – Sub-frame format (linear PCM application)
4.1.2 Frame format

A frame is uniquely composed of two sub-frames (see Figure 2). For linear coded audio

applications, the rate of transmission of frames normally corresponds exactly to the source

sampling frequency.

In 2-channel operation mode, the samples taken from both channels are transmitted by time

multiplexing in consecutive sub-frames. The first sub-frame (left or "A" channel in

stereophonic operation and primary channel in monophonic operation) normally starts with

preamble "M". However, the preamble changes to preamble "B" once every 192 frames to

identify the start of the block structure used to organize the channel status information. The

second sub-frame (right or "B" channel in stereophonic operation and secondary channel in

monophonic operation) always starts with preamble "W".

In single channel operation mode in a professional application, the frame format is the same

as in the 2-channel mode. Data is carried in the first sub-frame and may be duplicated in the

second sub-frame. If the second sub-frame is not carrying duplicate data, then time slot 28,

(validity flag) shall be set to logical "1".

NOTE For historical reasons preambles "B", "M" and "W" are, for use in professional applications, referred to as

"Z", "X" and "Y", respectively.
X Y Z Y X Y X
M Channel 1 W Channel 2 B Channel 1 W Channel 2 M Channel 1 W Channel 2 M
Sub-frame Sub-frame
Frame 191 Frame 0 Frame 1
Start of block
IEC 1552/08
Figure 2 – Frame format
4.2 Channel coding

To minimize the direct current (d.c.) component on the transmission line, to facilitate clock

recovery from the data stream and to make the interface insensitive to the polarity of

connections, time slots 4 to 31 are encoded in biphase-mark.

Each bit to be transmitted is represented by a symbol comprising two consecutive binary

states. The first state of a symbol is always different from the second state of the previous

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symbol. The second state of the symbol is identical to the first if the bit to be transmitted is

logical "0". However, it is different if the bit is logical "1" (see Figure 3).
Clock (twice bit rate)
Source coding
Channel coding (biphase mark)
IEC 1553/08
Figure 3 – Channel coding
4.3 Preambles

Preambles are specific patterns providing synchronization and identification of the sub-frames

and blocks.

To achieve synchronization within one sampling period and to make this process completely

reliable, these patterns violate the biphase-mark code rules, thereby avoiding the possibility of

data imitating the preambles.

A set of three preambles is used. These preambles are transmitted in the time allocated to

four time slots at the start of each sub-frame (time slots 0 to 3), and are represented by eight

successive states. The first state of the preamble is always different from the second state of

the previous symbol (representing the parity bit). Depending on this state the preambles are

as shown in Table 1.
Table 1 – Preamble coding
Preceding state 0 1
Preamble code Channel coding
“B” or “Z” 11101000 00010111 Sub-frame 1 and
(see note to 4.1.2) the start of the block
“M” or “X” 11100010 00011101 Sub-frame 1
“W” or “Y” 11100100 00011011 Sub-frame 2

Like biphase code, these preambles are d.c. free and provide clock recovery. They differ in at

least two states from any valid biphase sequence.
Figure 4 represents preamble "M".

NOTE Owing to the even-parity bit in time slot 31, all preambles start with a transition in the same direction

(see 4.1.1). Thus, only one of these sets of preambles is, in practice, transmitted through the interface. However, it

is necessary for both sets to be decodable because either polarity is possible in a connection.

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60958
...

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