Road vehicles -- Media Oriented Systems Transport (MOST)

This document specifies the conformance test plan (CTP) for the data link layer for MOST, a synchronous time-division-multiplexing network, as specified in ISO 21806-6. This document specifies conformance test cases (CTCs) in the following categories: — network frames; — allocation channel; — protected system channel; — timestamp channel; — flow control; — cyclic redundancy check; — arbitration; — default packet channel. Interoperability testing is not in the scope of this document.

Véhicules routiers -- Système de transport axé sur les médias

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Published
Publication Date
17-Sep-2020
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5060 - Close of voting Proof returned by Secretariat
Start Date
03-Aug-2020
Completion Date
03-Aug-2020
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INTERNATIONAL ISO
STANDARD 21806-7
First edition
2020-09
Road vehicles — Media Oriented
Systems Transport (MOST) —
Part 7:
Data link layer conformance test plan
Véhicules routiers — Système de transport axé sur les médias —
Partie 7: Plan d'essais de conformité de la couche de liaison de données
Reference number
ISO 21806-7:2020(E)
ISO 2020
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ISO 21806-7:2020(E)
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© ISO 2020

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ii © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

4.1 Symbols ......................................................................................................................................................................................................... 2

4.2 Abbreviated terms ............................................................................................................................................................................... 2

5 Conventions ............................................................................................................................................................................................................... 2

6 CTP overview ............................................................................................................................................................................................................ 2

6.1 Test set-up ................................................................................................................................................................................................... 2

6.2 Conformance test plan organisation .................................................................................................................................... 4

7 CTP general information .............................................................................................................................................................................. 4

8 CTC specification .................................................................................................................................................................................................. 5

8.1 Network frame CTCs .......................................................................................................................................................................... 5

8.1.1 CTC_7.1-1 – PREAMBLE test .................................................................................................................................. 5

8.1.2 CTC_7.1-2 – General bit order test .................................................................................................................... 5

8.1.3 CTC_7.1-3 – Node counter bit order test ..................................................................................................... 6

8.2 Allocation channel CTCs.................................................................................................................................................................. 7

8.2.1 CTC_7.2-1 – Allocation words ............................................................................................................................... 7

8.2.2 CTC_7.2-2 – Start of Allocation Frame (SOAF) test ............................................................................. 7

8.2.3 CTC_7.2-3 – Reporting format test ................................................................................................................... 8

8.2.4 CTC_7.2-4 – TimingMaster clears the allocation word test ......................................................... 9

8.2.5 CTC_7.2-5 – TimingMaster not arbitrating test ..................................................................................... 9

8.2.6 CTC_7.2-6 – TimingSlave forwards allocation word test ............................................................10

8.3 Protected system channel CTCs .............................................................................................................................................11

8.3.1 CTC_7.3-1 – Size and location test .................................................................................................................11

8.3.2 CTC_7.3-2 – Reaction on CRC error test ....................................................................................................12

8.3.3 CTC_7.3-3 – Node counter test ..........................................................................................................................12

8.3.4 CTC_7.3-4 – TimingMaster visible nodes value test .......................................................................13

8.3.5 CTC_7.3-5 – System flags test .............................................................................................................................13

8.4 CTC_7.4-1 – Timestamp channel frame test ...............................................................................................................14

8.5 Flow control CTCs .............................................................................................................................................................................15

8.5.1 CTC_7.5-1 – Target address not matching test ....................................................................................15

8.5.2 CTC_7.5-2 – Modification of the PACK byte test .................................................................................16

8.6 Cyclic redundancy check CTCs ...............................................................................................................................................17

8.6.1 CTC_7.6-1 – No reception of channel frame test ................................................................................17

8.6.2 CTC_7.6-2 – CRC acknowledge test ...............................................................................................................18

8.7 Arbitration CTCs .................................................................................................................................................................................19

8.7.1 CTC_7.7-1 – Only sending nodes participate test ..............................................................................19

8.7.2 CTC_7.7-2 – Copy Arb1 and WAIT test .......................................................................................................19

8.7.3 CTC_7.7-3 – Copy Arb2 into Arb3 test ........................................................................................................20

8.7.4 CTC_7.7-4 – Forward WAIT test .......................................................................................................................21

8.8 CTC_7.8-1 – Default packet channel test ........................................................................................................................22

Bibliography .............................................................................................................................................................................................................................23

© ISO 2020 – All rights reserved iii
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ISO 21806-7:2020(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 31,

Data communication.
A list of all parts in the ISO 21806 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
Introduction

The Media Oriented Systems Transport (MOST) communication technology was initially developed at

the end of the 1990s in order to support complex audio applications in cars. The MOST Cooperation was

founded in 1998 with the goal to develop and enable the technology for the automotive industry. Today,

MOST enables the transport of high quality of service (QoS) audio and video together with packet data

and real-time control to support modern automotive multimedia and similar applications. MOST is a

function-oriented communication technology to network a variety of multimedia devices comprising

one or more MOST nodes.
Figure 1 shows a MOST network example.
Figure 1 — MOST network example
The MOST communication technology provides:
— synchronous and isochronous streaming,
— small overhead for administrative communication control,
— a functional and hierarchical system model,
— API standardization through a function block (FBlock) framework,
— free partitioning of functionality to real devices,
— service discovery and notification, and
[2]

— flexibly scalable automotive-ready Ethernet communication according to ISO/IEC/IEEE 8802-3 .

MOST is a synchronous time-division-multiplexing (TDM) network that transports different data types

on separate channels at low latency. MOST supports different bit rates and physical layers. The network

clock is provided with a continuous data signal.

1) MOST is the registered trademark of Microchip Technology Inc. This information is given for the convenience

of users of this document and does not constitute an endorsement by ISO.
© ISO 2020 – All rights reserved v
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ISO 21806-7:2020(E)

Within the synchronous base data signal, the content of multiple streaming connections and control

data is transported. For streaming data connections, bandwidth is reserved to avoid interruptions,

collisions, or delays in the transport of the data stream.

MOST specifies mechanisms for sending anisochronous, packet-based data in addition to control data

and streaming data. The transmission of packet-based data is separated from the transmission of

control data and streaming data. None of them interfere with each other.

A MOST network consists of devices that are connected to one common control channel and packet

channel.

In summary, MOST is a network that has mechanisms to transport the various signals and data streams

that occur in multimedia and infotainment systems.

The ISO standards maintenance portal (https:// standards .iso .org/ iso/ ) provides references to MOST

specifications implemented in today's road vehicles because easy access via hyperlinks to these

specifications is necessary. It references documents that are normative or informative for the MOST

versions 4V0, 3V1, 3V0, and 2V5.

The ISO 21806 series has been established in order to specify requirements and recommendations

for implementing the MOST communication technology into multimedia devices and to provide

conformance test plans for implementing related test tools and test procedures.

To achieve this, the ISO 21806 series is based on the open systems interconnection (OSI) basic reference

[1] [3]

model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731 , which structures communication

systems into seven layers as shown in Figure 2. Stream transmission applications use a direct stream

data interface (transparent) to the data link layer.
vi © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
Figure 2 — The ISO 21806 series reference according to the OSI model

The International Organization for Standardization (ISO) draws attention to the fact that it is claimed

that compliance with this document may involve the use of a patent.

ISO takes no position concerning the evidence, validity and scope of this patent right.

The holder of this patent right has assured ISO that he/she is willing to negotiate licences under

reasonable and non-discriminatory terms and conditions with applicants throughout the world. In

this respect, the statement of the holder of this patent right is registered with ISO. Information may be

obtained from the patent database available at www .iso .org/ patents.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights other than those in the patent database. ISO shall not be held responsible for identifying

any or all such patent rights.
© ISO 2020 – All rights reserved vii
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INTERNATIONAL STANDARD ISO 21806-7:2020(E)
Road vehicles — Media Oriented Systems Transport
(MOST) —
Part 7:
Data link layer conformance test plan
1 Scope

This document specifies the conformance test plan (CTP) for the data link layer for MOST, a synchronous

time-division-multiplexing network, as specified in ISO 21806-6.

This document specifies conformance test cases (CTCs) in the following categories:

— network frames;
— allocation channel;
— protected system channel;
— timestamp channel;
— flow control;
— cyclic redundancy check;
— arbitration;
— default packet channel.
Interoperability testing is not in the scope of this document.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

ISO/IEC 9646-1, Information technology — Open Systems Interconnection — Conformance testing

methodology and framework — Part 1: General concepts

ISO 21806-1, Road vehicles — Media Oriented Systems Transport (MOST) — Part 1: General information

and definitions

ISO 21806-6, Road vehicles — Media Oriented Systems Transport (MOST) — Part 6: Data link layer

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 21806-1, ISO 21806-6,

ISO/IEC 9646-1, and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2020 – All rights reserved 1
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ISO 21806-7:2020(E)
3.1
REPEAT
pseudo code command for an iteration
3.2
REPEAT END
pseudo code command for ending an iteration
4 Symbols and abbreviated terms
4.1 Symbols
--- empty cell/undefined
N packet bandwidth control
PBC
N total number of bytes per frame
TNBPF
4.2 Abbreviated terms

For the purposes of this document, the abbreviated terms given in ISO 21806-1, ISO 21806-6, and the

following apply.
CACK CRC acknowledge
CTC conformance test case
CTP conformance test plan
IUT implementation under test
LSb least significant bit
LT lower tester
MSb most significant bit
OSI Open Systems Interconnection
PACK pre-emptive acknowledge
SOAF start of allocation frame
UT upper tester
5 Conventions
[3]

This document is based on OSI service conventions as specified in ISO/IEC 10731 and ISO/IEC 9646-1

for conformance test system set-up.
6 CTP overview
6.1 Test set-up

All CTCs are based on the same test set-up with an upper tester (UT) and a lower tester (LT). The LT

contains the lower tester pre-IUT (LT pre-IUT) and the lower tester post-IUT (LT post-IUT).

2 © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
Figure 3 specifies the test set-up.
Figure 3 — Test set-up
Every CTC specifies the roles of the LT pre-IUT and the LT post-IUT.

During testing of the MOST device that implements the IUT, avoid over-temperature by following the

manufacturer recommendations regarding cooling.

The power supply of the MOST device that contains the IUT is adjustable and the power consumption can

be monitored by the UT. This is necessary to determine whether a node enters s_NetInterface_Sleep.

A MOST device contains one or more nodes, which are connected to an external MOST physical interface.

One of the nodes contains the implementation under test (IUT). All tests and timings, specified by the

CTP, are related to the external MOST physical interface.
Figure 4 shows a MOST device with one node and a MOST device with three nodes.
© ISO 2020 – All rights reserved 3
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ISO 21806-7:2020(E)
Key
1 external MOST physical interface
2 internal MOST physical interface
Figure 4 — MOST device with one node and MOST device with three nodes
6.2 Conformance test plan organisation

CTCs are independent of one another. Each CTC checks the behaviour of the IUT for requirements stated

in ISO 21806-6. Within CTCs, which require variations of individual parameters, each specified value of

the parameter is iterated.
7 CTP general information

The following network frame elements require no initiative by the IUT and are observable in the MOST

network during black box testing:
a) network frame indicators:
— PREAMBLE;
— START;
— END.
b) system flags;
c) node counter;
d) visible nodes value;
e) packet bandwidth control (N );
PBC
f) network frame data bytes:
— control frame PACK and CACK;
— packet frame PACK and CACK;
— Ethernet frame PACK and CACK.
g) allocation frame:
— SOAF;
— allocation-defend frame;
— arbitration-result frame.
4 © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
8 CTC specification
8.1 Network frame CTCs
8.1.1 CTC_7.1-1 – PREAMBLE test
Table 1 specifies the CTC_7.1-1 – PREAMBLE test.
Table 1 — CTC_7.1-1 – PREAMBLE test
Item Content
CTC # – Title CTC_7.1-1 – PREAMBLE test

Purpose This CTC verifies that a network frame consists of a network indicator of type PREAMBLE,

indicating the start of the network frame, followed by a number of data bytes.
This test applies to all MOST devices.
Reference ISO 21806-6:2020: REQ 2.63 DLL – Network frame – PREAMBLE
Prerequisite Ring closed
Set-up — The IUT is contained in the TimingMaster or a TimingSlave;

— If the IUT is part of a MOST device that does not contain the TimingMaster, the LT pre-IUT

shall be the TimingMaster;

— If the IUT is part of a MOST device that contains the TimingMaster, the LT pre-IUT shall be

a TimingSlave;
— The LT post-IUT shall be a listen-only node.
Step 1. The LT post-IUT shall acquire at least one network frame.

2. The UT shall determine the presence of exactly one PREAMBLE in the network frame.

3. The UT shall determine the presence of data bytes after the PREAMBLE by examining the

visible nodes value, taken from the network frame.
Iteration Not applicable

Expected Step 3: IUT ok: within the duration of a network frame, the PREAMBLE appears once. The PRE-

response AMBLE is followed by data bytes.

Step 2: IUT not ok (1): within the duration of a network frame, the PREAMBLE does not appear.

Step 2: IUT not ok (2): within the duration of a network frame, the PREAMBLE appears more

than once.
Step 3: IUT not ok (3): after the PREAMBLE, no data bytes follow.
Remark ---
8.1.2 CTC_7.1-2 – General bit order test
Table 2 specifies the general bit order test.
Table 2 — CTC_7.1-2 – General bit order test
Item Content
CTC # – Title CTC_7.1-2 – General bit order test

Purpose This CTC verifies that the correct order is present for data bytes in the network frame that are

supposed to be transmitted in most significant bit (MSb) first order.
This CTC applies to all MOST devices.
Reference ISO 21806-6:2020: REQ 2.64 DLL – Network frame – General bit order
Prerequisite Ring closed
© ISO 2020 – All rights reserved 5
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ISO 21806-7:2020(E)
Table 2 (continued)
Item Content
Set-up — The IUT is contained in the TimingMaster or a TimingSlave.

— If the IUT is part of a MOST device that does not contain the TimingMaster, the LT pre-IUT

shall be the TimingMaster.

— If the IUT is part of a MOST device that contains the TimingMaster, the LT pre-IUT shall be

a TimingSlave.
— The LT post-IUT shall be a listen-only node.
Step 1. The LT post-IUT shall acquire one complete network frame.

2. The UT shall determine the bit order of the visible nodes value, taken from the network

frame.
Iteration Not applicable
Expected Step 2: IUT ok: the bit order of the visible nodes value is MSb.
response
Step 2: IUT not ok (1): the bit order of the visible nodes value is not MSb.
Remark ---
8.1.3 CTC_7.1-3 – Node counter bit order test
Table 3 specifies the node counter bit order test.
Table 3 — CTC_7.1-3 – Node counter bit order test
Item Content
CTC # – Title CTC_7.1-3 – Node counter bit order test

Purpose This CTC verifies that the correct order is present for the node counter in the network frame

that is supposed to be transmitted in least significant bit (LSb) first order.
This CTC applies to all MOST devices.

Reference ISO 21806-6:2020: REQ 2.65 DLL – Network frame – Node counter bit order

Prerequisite Ring closed
Set-up — The IUT is contained in the TimingMaster or a TimingSlave.

— If the IUT is part of a MOST device that does not contain the TimingMaster, the LT pre-IUT

shall be the TimingMaster.

— If the IUT is part of a MOST device that contains the TimingMaster, the LT pre-IUT shall be

a TimingSlave.
— The LT post-IUT shall be a listen-only node.
Step 1. The LT post-IUT shall acquire one complete network frame.

2. The UT shall determine the bit order of the node counter value, taken from the network

frame.
Iteration Not applicable
Expected Step 2: IUT ok: the bit order of the node counter value is LSb.
response
Step 2: IUT not ok: the bit order of the node counter value is not LSb.
Remark ---
6 © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
8.2 Allocation channel CTCs
8.2.1 CTC_7.2-1 – Allocation words
Table 4 specifies the allocation words test.
Table 4 — CTC_7.2-1 – Allocation words
Item Content
CTC # – Title CTC_7.2-1 – Allocation words

Purpose This CTC verifies the existence and completeness of the allocation frame.

This CTC applies to all MOST devices.
Reference ISO 21806-6:2020: REQ 2.66 DLL – Allocation channel – Allocation words
Prerequisite Ring closed
Set-up — The IUT is contained in the TimingMaster or a TimingSlave.

— If the IUT is part of a MOST device that does not contain the TimingMaster, the LT pre-IUT

shall be the TimingMaster.

— If the IUT is part of a MOST device that contains the TimingMaster, the LT pre-IUT shall be

a TimingSlave.
— The LT post-IUT shall be a listen-only node.

Step 1. The LT post-IUT shall acquire as many network frames as necessary to obtain a complete

allocation frame.

2. The UT shall determine whether the correct amount of allocation words (N ) is present

TNBPF
in the allocation frame.
Iteration Not applicable

Expected Step 2: IUT ok: the allocation frame is present and contains the correct number of alloca-

response tion words.
Step 2: IUT not ok (1): the allocation frame cannot be assembled.

Step 2: IUT not ok (2): the allocation frame does not contain the correct number of alloca-

tion words.
Remark ---
8.2.2 CTC_7.2-2 – Start of Allocation Frame (SOAF) test
Table 5 specifies the start of allocation frame (SOAF) test.
Table 5 — CTC_7.2-2 – Start of allocation frame (SOAF) test
Item Content
CTC # – Title CTC_7.2-2 – Start of allocation frame (SOAF) test
Purpose This CTC verifies:

— that the structure of the received allocation word, SOAF format, contains the START

indicator in bits 15 to 8 and arbitrary data in bits 7 to 0,

— that the IUT sends an allocation word in SOAF format if it is the TimingMaster, and

— that the IUT does not alter the SOAF format if it is a TimingSlave.
This CTC applies to all MOST devices.
© ISO 2020 – All rights reserved 7
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ISO 21806-7:2020(E)
Table 5 (continued)
Item Content
Reference ISO 21806-6:2020:
REQ 2.67 DLL – Allocation channel – SOAF format;
REQ 2.75 DLL – Allocation channel –TimingMaster sends SOAF;
REQ 2.81 DLL – Allocation channel – START.
Prerequisite Ring closed
Set-up — The IUT is contained in the TimingMaster or a TimingSlave.

— If the IUT is part of a MOST device that does not contain the TimingMaster, the LT pre-IUT

shall be the TimingMaster.

— If the IUT is part of a MOST device that contains the TimingMaster, the LT pre-IUT shall be

a TimingSlave.
— The LT post-IUT shall be a listen-only node.

Step 1. The LT post-IUT shall acquire as many network frames as necessary to obtain a complete

allocation frame.
2. The UT shall determine whether the SOAF format is represented correctly.
Iteration Not applicable

Expected Step 2: IUT ok: the SOAF appears and the SOAF format is represented correctly.

response

Step 2: IUT not ok (1): the IUT does not write an allocation word in SOAF format or the SOAF

format is not represented correctly.
Step 2: IUT not ok (2): a TimingSlave alters the SOAF format.
Remark ---
8.2.3 CTC_7.2-3 – Reporting format test
Table 6 specifies the reporting format test.
Table 6 — CTC_7.2-3 – Reporting format test
Item Content
CTC # – Title CTC_7.2-3 – Reporting format test

Purpose This CTC verifies that the structure of the received allocation word in reporting format contains:

— the CRC in bits 15 to 12,
— zeros in bits 11 to 10,
— the new allocation flag in bit 9,
— and the connection label in bits 8 to 0.
This CTC applies to all MOST devices.
Reference ISO 21806-6:2020: REQ 2.66 DLL – Allocation channel – Allocation words
Prerequisite Ring closed
Set-up — The IUT is contained in the TimingMaster or a TimingSlave.

— If the IUT is part of a MOST device that does not contain the TimingMaster, the LT pre-IUT

shall be the TimingMaster.

— If the IUT is part of a MOST device that contains the TimingMaster, the LT pre-IUT shall be

a TimingSlave.
— The LT post-IUT shall be a listen-only node.
8 © ISO 2020 – All rights reserved
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ISO 21806-7:2020(E)
Table 6 (continued)
Item Content

Step 1. The LT post-IUT shall acquire as many network frames as necessary to obtain a complete

allocation frame.
2. The UT shall det
...

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