ISO 3934:2021

Rubber, vulcanized and thermoplastic — Preformed gaskets used in buildings — Classification, specifications and test methods

This document specifies a system of classification of materials used in preformed gaskets for buildings. It applies to the following products: a) gaskets for use round the inside of door or window casings, i.e. weatherstripping (dynamic gaskets); b) gaskets for glazing (static gaskets); c) gaskets for use round infilling; d) gaskets for use between facade parts; e) gaskets for use between masonry walls. In addition to specifying the characteristics required for the constituent materials, some functional tests on the gaskets themselves are specified. The corresponding test procedures are given in Annexes A to E. This document applies to preformed gaskets made from vulcanized or thermoplastic rubber. It also applies to preformed gaskets made of cellular rubber designed for use at temperatures between −20 °C and +55 °C (thermal conditions category P1) and between −40 °C and +70 °C (thermal conditions category P3) (see Clause 4).

Caoutchouc vulcanisé et thermoplastique — Profilés d'étanchéité utilisés dans le bâtiment — Classification, spécifications et méthodes d'essai

General Information

• Status: Published
• Publication Date: 18-Oct-2021
• ICS: 83.140.50 - Seals
• ICS: 91.100.50 - Binders. Sealing materials
• Technical Committee: ISO/TC 45/SC 4 - Products (other than hoses)
• Drafting Committee: ISO/TC 45/SC 4/WG 7 - Material specification
• Current Stage: 6060 - International Standard published
• Start Date: 19-Oct-2021
• Due Date: 12-Dec-2021
• Completion Date: 19-Oct-2021

Relations

• Revises: ISO 3934:2002 - Rubber, vulcanized and thermoplastic — Preformed gaskets used in buildings — Classification, specifications and test methods
• Effective Date: 23-Apr-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 3934
Third edition
2021-10
Rubber, vulcanized and
thermoplastic — Preformed gaskets
used in buildings — Classification,
specifications and test methods
Caoutchouc vulcanisé et thermoplastique — Profilés d'étanchéité
utilisés dans le bâtiment — Classification, spécifications et méthodes
d'essai
Reference number
ISO 3934:2021(E)
© ISO 2021

---------------------- Page: 1 ----------------------
ISO 3934:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 3934:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Environmental conditions . 3
5 Classification and specification .3
5.1 Classification . 3
5.2 Specifications . 4
6 Test pieces .4
Annex A (normative) Working compression range .11
Annex B (normative) Compression force .12
Annex C (normative) Compression recovery test .15
Annex D (normative) Stress relaxation under specified compression .17
Annex E (normative) Variation in length .19
iii
© ISO 2021 – All rights reserved

---------------------- Page: 3 ----------------------
ISO 3934:2021(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 45, Rubber and rubber products,
Subcommittee SC 4, Products (other than hoses).
This third edition cancels and replaces the second edition (ISO 3934:2002), which has been technically
revised.
The main changes to the previous edition are as follows:
— requirements on estimation of lifetime have been added;
— hardness tolerance has increased;
— references have been updated.
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 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 3934:2021(E)
Introduction
Preformed gaskets used in buildings have conditions of use which differ depending on their function
and position in the building. When preparing this document, it was felt necessary to take into account
the various conditions to which the gaskets are subjected in order to define the material specifications.
The tests take into account the static and dynamic stresses to which the gaskets are subjected.
v
© ISO 2021 – All rights reserved

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 3934:2021(E)
Rubber, vulcanized and thermoplastic — Preformed
gaskets used in buildings — Classification, specifications
and test methods
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with
its use. It is the responsibility of the user of this document to establish appropriate safety and
health practices and to determine the applicability of any national regulatory conditions.
1 Scope
This document specifies a system of classification of materials used in preformed gaskets for buildings.
It applies to the following products:
a) gaskets for use round the inside of door or window casings, i.e. weatherstripping (dynamic gaskets);
b) gaskets for glazing (static gaskets);
c) gaskets for use round infilling;
d) gaskets for use between facade parts;
e) gaskets for use between masonry walls.
In addition to specifying the characteristics required for the constituent materials, some functional tests
on the gaskets themselves are specified. The corresponding test procedures are given in Annexes A to E.
This document applies to preformed gaskets made from vulcanized or thermoplastic rubber. It also
applies to preformed gaskets made of cellular rubber designed for use at temperatures between −20 °C
and +55 °C (thermal conditions category P ) and between −40 °C and +70 °C (thermal conditions
1
category P ) (see Clause 4).
3
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 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties
ISO 48-4, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 4: Indentation
hardness by durometer method (Shore hardness)
ISO 105-A02, Textiles — Tests for colour fastness — Part A02: Grey scale for assessing change in colour
ISO 188:2011, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests
ISO 812, Rubber, vulcanized or thermoplastic — Determination of low-temperature brittleness
ISO 815-1, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 1: At ambient
or elevated temperatures
ISO 815-2, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 2: At low
temperatures
1
© ISO 2021 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 3934:2021(E)
ISO 1431-1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and
dynamic strain testing
ISO 2285:2019, Rubber, vulcanized or thermoplastic — Determination of tension set under constant
elongation, and of tension set, elongation and creep under constant tensile load
ISO 3384-1:2019, Rubber, vulcanized or thermoplastic — Determination of stress relaxation in compression
— Part 1: Testing at constant temperature
ISO 4892-2, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps
ISO 11346, Rubber, vulcanized or thermoplastic — Estimation of life-time and maximum temperature of
use
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1
compression force
force needed to compress a test piece through its working range to its minimum width (3.3)
3.2
compression recovery
ability of a gasket to recover its shape after being compressed through its working range
3.3
minimum width
lower limit of the working compression range (3.7)
Note 1 to entry: For a glazing gasket, the minimum width is the sum of the gaps between the glass and the
frame on each side of the glass. For weatherstripping, it is the gap between the door or window and the casing,
measured at the hinge side.
Note 2 to entry: It is recommended that the minimum width of weatherstripping and the minimum clearance
between glazing and frame for a glazing gasket be agreed by consultation between designer, manufacturer and
user
3.4
sample
complete batch of test material (gaskets) as supplied by the manufacturer for test purposes and from
which test pieces are cut
3.5
stress relaxation
time-dependent decrease in stress at a constant deformation
3.6
weathering resistance
resistance to combined detrimental influences of the outdoor environment (e.g. sunlight, ozone, oxygen,
humidity, temperature) on a material
2
  © ISO 2021 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 3934:2021(E)
3.7
working compression range
range, stated by the manufacturer, through which the gasket performs its function of being compressed
or otherwise deformed when used in any particular product
Note 1 to entry: See Annex A.
EXAMPLE For a gasket of free height (3.8) 7,5 mm, the manufacturer states a working range of 3 mm to
6 mm.
3.8
free height
height of a gasket measured without causing any significant deformation
Note 1 to entry: See Figure 1.
Figure 1 — Example of measurement of free height
4 Environmental conditions
The conditions to which gaskets may be subjected in the working environment are divided into the
following categories:
a) Thermal conditions (depending on the climate and the position in the construction)
— P : temperature of preformed gasket −20 °C to +55 °C
1
— P : temperature of preformed gasket –20 °C to +85 °C
2
— P : temperature of preformed gasket –40 °C to +70 °C
3
— P : temperature of preformed gasket –40 °C to +100 °C
4
b) Mechanical conditions
— X: static uses (see Table 1), i.e. between fixed elements
— Y: dynamic uses (see Table 1), i.e. between moving elements
c) Weathering
— R : protected from solar radiation
1
— R : exposed to solar radiation
2
5 Classification and specification
5.1 Classification
From the results of the tests carried out in accordance with this document, the classification of a
particular type of gasket shall be determined using Table 1. The numbers from Table 1, taken in the
order given, form the classification code for that gasket, viz:
3
© ISO 2021 – All rights reserved

---------------------- Page: 8 ----------------------
ISO 3934:2021(E)
— A: type of gasket
— B: working compression range
— C: compression force
— D: working temperature range
— E: compression recovery
— F: stress relaxation
— G: weathering resistance
Figure 2 gives a typical example of a classification code.
5.2 Specifications
The characteristics for the different classification criteria shall meet the requirements specified in
Tables 2 to 9.
6 Test pieces
Test pieces shall be prepared in accordance with the relevant standard test method or the relevant
annex of this document and, whenever possible, shall be cut from the gasket to be tested.
Failing this, they shall be taken from extruded ribbon (2 mm thick, 30 mm in width) or from
appropriately dimensioned test slabs prepared from the same batch of material used to produce the
gaskets being assessed and obtained under conditions that have been shown by experience to give
comparable results.
If measurements are made on test pieces not conforming to the standard referenced in Tables 2 to 9
(e.g. part of a gasket), the results can be different and the requirements to be met shall be subject to
agreement between the interested parties.
Table 1 — Classification of gaskets
Class
Code-
Characteristic
letter
0 1 2 3 4 5 6 7 8 9
X: static use
A Type of gasket
Y: dynamic use
Working compression
> 1 > 2 > 4 > 6 > 8 > 10 > 15
range (mm)
B u ≤ 1 but but but but but but but > 30
Measured in accord-
u ≤ 2 u ≤ 4 u ≤ 6 u ≤ 8 u ≤ 10 u ≤ 15 u ≤ 30
ance with Annex A
Compression force
> 50 > 100 > 700
> 10 > 20 > 200 > 500
(N/m)
but bu
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 3934
ISO/TC 45/SC 4
Rubber, vulcanized and
Secretariat: DSM
thermoplastic — Preformed gaskets
Voting begins on:
2021­07­14 used in buildings — Classification,
specifications and test methods
Voting terminates on:
2021­09­08
Caoutchouc vulcanisé et thermoplastique — Profilés d'étanchéité
utilisés dans le bâtiment — Classification, spécifications et méthodes
d'essai
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 3934:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021

---------------------- Page: 1 ----------------------
ISO/FDIS 3934:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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
CH­1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 3934:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Environmental conditions . 3
5 Classification and specification . 3
5.1 Classification . 3
5.2 Specifications. 4
6 Test pieces . 4
Annex A (normative) Working compression range .11
Annex B (normative) Compression force .12
Annex C (normative) Compression recovery test .15
Annex D (normative) Stress relaxation under specified compression .17
Annex E (normative) Variation in length .19
© ISO 2021 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/FDIS 3934:2021(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 non­governmental, 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 45, Rubber and rubber products,
Subcommittee SC 4, Products (other than hoses).
This third edition cancels and replaces the second edition (ISO 3934:2002), which has been technically
revised.
The main changes to the previous edition are as follows:
— requirements on estimation of lifetime have been added;
— hardness tolerance has increased
— references have been updated.
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 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/FDIS 3934:2021(E)

Introduction
Preformed gaskets used in buildings have conditions of use which differ depending on their function
and position in the building. When preparing this document, it was felt necessary to take into account
the various conditions to which the gaskets are subjected in order to define the material specifications.
The tests take into account the static and dynamic stresses to which the gaskets are subjected.
© ISO 2021 – All rights reserved v

---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 3934:2021(E)
Rubber, vulcanized and thermoplastic — Preformed
gaskets used in buildings — Classification, specifications
and test methods
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with
its use. It is the responsibility of the user of this document to establish appropriate safety and
health practices and to determine the applicability of any national regulatory conditions.
1 Scope
This document specifies a system of classification of materials used in preformed gaskets for buildings.
It applies to the following products:
a) gaskets for use round the inside of door or window casings, i.e. weatherstripping (dynamic gaskets);
b) gaskets for glazing (static gaskets);
c) gaskets for use round infilling;
d) gaskets for use between facade parts;
e) gaskets for use between masonry walls.
In addition to specifying the characteristics required for the constituent materials, some functional
tests on the gaskets themselves are specified. The corresponding test procedures are given in Annexes A
to E.
This document applies to preformed gaskets made from vulcanized or thermoplastic rubber. It also
applies to preformed gaskets made of cellular rubber designed for use at temperatures between −20 °C
and +55 °C (thermal conditions category P ) and between −40 °C and +70 °C (thermal conditions
1
category P ) (see Clause 4).
3
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 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties
ISO 48­4, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 4: Indentation
hardness by durometer method (Shore hardness)
ISO 105­A02, Textiles — Tests for colour fastness — Part A02: Grey scale for assessing change in colour
ISO 188:2011, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests
ISO 812, Rubber, vulcanized or thermoplastic — Determination of low-temperature brittleness
ISO 815­1, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 1: At ambient
or elevated temperatures
ISO 815­2, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 2: At low
temperatures
© ISO 2021 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO/FDIS 3934:2021(E)

ISO 1431­1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and
dynamic strain testing
ISO 2285:2019, Rubber, vulcanized or thermoplastic — Determination of tension set under constant
elongation, and of tension set, elongation and creep under constant tensile load
ISO 3384­1:2019, Rubber, vulcanized or thermoplastic — Determination of stress relaxation in
compression — Part 1: Testing at constant temperature
ISO 4892­2, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps
ISO 11346, Rubber, vulcanized or thermoplastic — Estimation of life-time and maximum temperature of
use
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1
compression force
force needed to compress a test piece through its working range to its minimum width (3.3)
3.2
compression recovery
ability of a gasket to recover its shape after being compressed through its working range
3.3
minimum width
lower limit of the working compression range (3.7)
Note 1 to entry: For a glazing gasket, the minimum width is the sum of the gaps between the glass and the
frame on each side of the glass. For weatherstripping, it is the gap between the door or window and the casing,
measured at the hinge side.
Note 2 to entry: It is recommended that the minimum width of weatherstripping and the minimum clearance
between glazing and frame for a glazing gasket be agreed by consultation between designer, manufacturer and
user
3.4
sample
complete batch of test material (gaskets) as supplied by the manufacturer for test purposes and from
which test pieces are cut
3.5
stress relaxation
time­dependent decrease in stress at a constant deformation
3.6
weathering resistance
resistance to combined detrimental influences of the outdoor environment (e.g. sunlight, ozone, oxygen,
humidity, temperature) on a material
2 © ISO 2021 – All rights reserved

---------------------- Page: 7 ----------------------
ISO/FDIS 3934:2021(E)

3.7
working compression range
range, stated by the manufacturer, through which the gasket performs its function of being compressed
or otherwise deformed when used in any particular product
Note 1 to entry: See Annex A.
EXAMPLE For a gasket of free height (3.8) 7,5 mm, the manufacturer states a working range of 3 mm to
6 mm.
3.8
free height
height of a gasket measured without causing any significant deformation
Note 1 to entry: See Figure 1.
Figure 1 — Example of measurement of free height
4 Environmental conditions
The conditions to which gaskets may be subjected in the working environment are divided into the
following categories:
a) Thermal conditions (depending on the climate and the position in the construction)
— P : temperature of preformed gasket −20 °C to +55 °C
1
— P : temperature of preformed gasket –20 °C to +85 °C
2
— P : temperature of preformed gasket –40 °C to +70 °C
3
— P : temperature of preformed gasket –40 °C to +100 °C
4
b) Mechanical conditions
— X: static uses (see Table 1), i.e. between fixed elements
— Y: dynamic uses (see Table 1), i.e. between moving elements
c) Weathering
— R : protected from solar radiation
1
— R : exposed to solar radiation
2
5 Classification and specification
5.1 Classification
From the results of the tests carried out in accordance with this document, the classification of a
particular type of gasket shall be determined using Table 1. The numbers from Table 1, taken in the
order given, form the classification code for that gasket, viz:
© ISO 2021 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO/FDIS 3934:2021(E)

— A: type of gasket
— B: working compression range
— C: compression force
— D: working temperature range
— E: compression recovery
— F: stress relaxation
— G: weathering resistance
Figure 2 gives a typical example of a classification code.
5.2 Specifications
The characteristics for the different classification criteria shall meet the requirements specified in
Tables 2 to 9.
6 Test pieces
Test pieces shall be prepared in accordance with the relevant standard test method or the relevant
annex of this document and, whenever possible, shall be cut from the gasket to be tested.
Failing this, they shall be taken from extruded ribbon (2 mm thick, 30 mm in width) or from
appropriately dimensioned test slabs prepared from the same batch of material used to produce the
gaskets being assessed and obtained under conditions that have been shown by experience to give
comparable results.
If measurements are made on test pieces not conforming to the standard referenced in Tables 2 to 9
(e.g. part of a gasket), the results can be different and the requirements to be met shall be s
...