SIST EN 61162-450:2011
(Main)Maritime navigation and radiocommunication equipment and systems - Digital interfaces - Part 450: Multiple talkers and multiple listeners - Light-weight ship systems interconnection
Maritime navigation and radiocommunication equipment and systems - Digital interfaces - Part 450: Multiple talkers and multiple listeners - Light-weight ship systems interconnection
This part of IEC 61162 specifies interface requirements and methods of test for high speed communication between shipboard navigation and radiocommunication equipment as well as between such systems and other ship systems that need to communicate with navigation and radio-communication equipment. This part of IEC 61162 is based on the application of an appropriate suite of existing international standards to provide a framework for implementing data transfer between devices on a shipboard Ethernet network. This standard provides a higher speed and higher capacity alternative to the IEC 61162-1 and IEC 61162-2 standards while retaining these standards’ basic data format. This standard provides a higher data capacity than IEC 61162-3. This standard specifies an Ethernet based bus type network where any listener may receive messages from any sender with the following properties. - This standard includes provisions for multicast distribution of information formatted according to IEC 61162-1, for example position fixes and other measurements, as well as provisions for transmission of general data blocks (binary image), for example between radar and VDR. - This standard is limited to protocols for equipment (Network nodes) connected to a single Ethernet network consisting only of OSI level one or two devices and cables (Network infrastructure). - This standard provides requirements only for equipment interfaces. By specifying protocols for transmission of IEC 61162-1 sentences and general binary image data these requirements will guarantee interoperability between equipment implementing this standard as well as a certain level of safe behaviour of the equipment itself. - This standard permits equipment using other protocols than those specified in this standard to share a network infrastructure provided that it is supplied with interfaces which satisfy the requirements described for ONF (see 4.6). - This standard does not contain any system requirements other than the ones that can be inferred from the sum of individual equipment requirements. Thus, to ascertain system properties that cannot be derived from equipment requirements alone, additional analysis or standards will be required. In particular, this applies to requirements to maintain system functionality in the face of a single point failure in equipment or networks. Informative Annex D contains guidance on how to address such issues.
Navigations- und Funkkommunikationsgeräte und -systeme für die Seeschifffahrt - Digitale Schnittstellen - Teil 450: Mehrere Datensender und mehrere Datenempfänger - Ethernet-Verbund
Matériels et systèmes de navigation et de radiocommunication maritimes - Interfaces numériques - Partie 450: Emetteurs multiples et récepteurs multiples - Interconnexion Ethernet
Pomorska navigacijska in radiokomunikacijska oprema in sistemi - Digitalni vmesniki - 450. del: Več govorcev in poslušalcev - Medsebojna povezava lažjih ladijskih sistemov
Ta del IEC 61162 določa zahteve za vmesnike in metode preskušanja visokohitrostne komunikacije med navigacijo na ladji in radiokomunikacijsko opremo ter med takimi sistemi in drugimi ladijskimi sistemi, ki so povezani z navigacijsko in radiokomunikacijsko opremo. Ta del IEC 61162 temelji na uporabi ustrezne zbirke obstoječih mednarodnih standardov in zagotavlja okvir za izvedbo prenosa podatkov med napravami v eternetnem omrežju na ladji. Ta standard navaja alternativo z večjo hitrostjo in večjo zmogljivostjo kot standarda IEC 61162-1 in IEC 61162-2, hkrati pa ohranja osnovni format podatkov iz teh standardov. Ta standard zagotavlja večjo zmogljivost za podatke kot IEC 61162-3. Ta standard določa na eternetu nameščeno omrežje z vodili, kjer lahko vsak poslušalec sprejema sporočila od katerega koli pošiljatelja z naslednjimi lastnostmi. - Ta standard vključuje določbe za večvrstno distribucijo informacij, formatiranih v skladu z IEC 61162-1, na primer pozicijskih navigacijskih točk in druge meritve, ter določbe za prenos splošnih podatkovnih sklopov (binarna slika), na primer med radarjem in VDR. - Ta standard je omejen na protokole za opremo (omrežne vozle), povezane z enojnim eternetnim omrežjem, sestavljenim iz samo ene ravni OSI ali dveh naprav in kablov (omrežna infrastruktura). - Ta standard podaja zahteve samo za vmesnike za opremo. Z določitvijo protokolov za prenos zaporedij IEC 61162-1 in splošnih podatkov binarnih slik te zahteve zagotavljajo medobratovalnost med opremo, ki izvaja ta standard, in določeno raven varnega vedenja same opreme. - Ta standard omogoča, da si oprema, ki uporablja protokole, ki niso določeni v tem standardu, deli omrežno infrastrukturo, pod pogojem, da je na voljo z vmesniki, ki ustrezajo zahtevam, opisanim za ONF (glej 4.6). - Ta standard ne vsebuje sistemskih zahtev, razen tistih, ki se lahko ugotovijo iz vsote posamičnih zahtev za opremo. Za zagotavljanje sistemskih lastnostih, ki jih ni mogoče izpeljati iz zahtev za opremo, je potrebna dodatna analiza ali standardi. Še zlasti to velja za zahteve za vzdrževanje funkcionalnosti sistema pri enotočkovni odpovedi opreme ali omrežij. Informativni dodatek D vsebuje vodilo o obravnavi takih težav.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.'LJLWDOQLMaritime navigation and radiocommunication equipment and systems - Digital interfaces - Part 450: Multiple talkers and multiple listeners - Light-weight ship systems interconnection47.020.70Navigacijska in krmilna opremaNavigation and control equipment33.060.01Radijske komunikacije na splošnoRadiocommunications in generalICS:Ta slovenski standard je istoveten z:EN 61162-450:2011SIST EN 61162-450:2011en01-oktober-2011SIST EN 61162-450:2011SLOVENSKI
STANDARD
SIST EN 61162-450:2011
EUROPEAN STANDARD EN 61162-450 NORME EUROPÉENNE
EUROPÄISCHE NORM August 2011
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2011 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61162-450:2011 E
ICS 47.020.70
English version
Maritime navigation and radiocommunication equipment and systems -
Digital interfaces -
Part 450: Multiple talkers and multiple listeners -
Ethernet interconnection (IEC 61162-450:2011)
Matériels et systèmes de navigation et de radiocommunication maritimes -
Interfaces numériques -
Partie 450: Emetteurs multiples et récepteurs multiples -
Interconnexion Ethernet (CEI 61162-450:2011)
Navigations- und Funkkommunikationsgeräte und -systeme für die Seeschifffahrt -
Digitale Schnittstellen -
Teil 450: Mehrere Datensenden und mehrere Datenempfänger -
Leichte Schiffssystemzusammenschaltung(IEC 61162-450:2011)
This European Standard was approved by CENELEC on 2011-07-15. 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, Croatia, 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.
SIST EN 61162-450:2011
EN 61162-450:2011 - 2 -
Foreword The text of document 80/615/FDIS, future edition 1 of IEC 61162-450, prepared by IEC TC 80, Maritime navigation and radiocommunication equipment and systems, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61162-450 on 2011-07-15. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. 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)
2012-04-15 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2014-07-15 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 61162-450:2011 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 60603-7 NOTE
Harmonized as EN 60603-7. IEC 60603-7-3 NOTE
Harmonized as EN 60603-7-3. IEC 60603-7-7 NOTE
Harmonized as EN 60603-7-7. IEC 61076-2-101 NOTE
Harmonized as EN 61076-2-101. IEC 61162-2 NOTE
Harmonized as EN 61162-2. IEC 61162-3 NOTE
Harmonized as EN 61162-3. IEC 61754-20 NOTE
Harmonized as EN 61754-20. IEC 61996-1 NOTE
Harmonized as EN 61996-1. IEC 62388 NOTE
Harmonized as EN 62388. __________
SIST EN 61162-450:2011
- 3 - EN 61162-450:2011
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
IEC 60825-2 - Safety of laser products -
Part 2: Safety of optical fibre communication systems (OFCS) EN 60825-2 -
IEC 60945 - Maritime navigation and radiocommunication equipment and systems - General requirements - Methods of testing and required test results EN 60945 -
IEC 61162-1 - Maritime navigation and radiocommunication equipment and systems - Digital interfaces - Part 1: Single talker and multiple listeners EN 61162-1 -
IEEE 802.3 - IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks -
Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications - -
ISOC RFC 768 - User Datagram Protocol - -
ISOC RFC 791 - Internet Protocol - DARPA Internet Program Protocol Specification - -
ISOC RFC 792 - Internet Control Message Protocol - -
ISOC RFC 826 - Ethernet Address Resolution Protocol - -
ISOC RFC 1918 - Address Allocation for Private Internets - -
ISOC RFC 2474 - Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers - -
ISOC RFC 5000 - Internet Official Protocol Standards - -
ISOC RFC 5227 - IPv4 Address Conflict Detection - -
ISOC RFC 5424 - The Syslog Protocol - -
NMEA 0183 2008 Standard for interfacing marine electronic devices - -
SIST EN 61162-450:2011
SIST EN 61162-450:2011
IEC 61162-450 Edition 1.0 2011-06 INTERNATIONAL STANDARD
Maritime navigation and radiocommunication equipment and systems – Digital interfaces –
Part 450: Multiple talkers and multiple listeners – Ethernet interconnection
INTERNATIONAL ELECTROTECHNICAL COMMISSION XB ICS 47.020.70 PRICE CODE ISBN 978-2-88912-492-3
® Registered trademark of the International Electrotechnical Commission ®
SIST EN 61162-450:2011
– 2 – 61162-450 IEC:2011(E) CONTENTS FOREWORD . 5 1 Scope . 7 2 Normative references . 7 3 Terms and definitions . 8 4 General network and equipment requirements . 11 4.1 Network topology example . 11 4.2 Basic requirements . 12 4.2.1 Requirements for equipment to be connected to the network . 12 4.2.2 Additional requirements for network infrastructure equipment . 12 4.3 Network function (NF) requirements . 13 4.3.1 General requirements . 13 4.3.2 Maximum data rate requirements . 13 4.3.3 Error logging function . 13 4.4 System function (SF) requirements . 15 4.4.1 General requirements . 15 4.4.2 Assignment of unique system function ID (SFI) . 15 4.4.3 Implementing configurable transmission groups . 15 4.5 Serial to network gateway function (SNGF) requirements . 16 4.5.1 General requirements . 16 4.5.2 Serial line output buffer management . 16 4.5.3 Datagram output requirements . 17 4.6 Other network function (ONF) requirements . 17 5 Low level network requirements. 17 5.1 Electrical and mechanical requirements. 17 5.2 Network protocol requirements . 19 5.3 IP Address assignment for equipment . 19 5.4 Multicast address range . 19 6 Transport layer specification . 19 6.1 General . 19 6.2 UDP messages. 20 6.2.1 UDP multicast protocol . 20 6.2.2 Use of multicast addresses and port numbers. 20 6.2.3 UDP checksum . 21 6.2.4 Datagram size . 21 7 Application layer specification . 22 7.1 Datagram header . 22 7.1.1 Valid header . 22 7.1.2 Error logging. 22 7.2 General IEC 61162-1 sentence transmissions . 22 7.2.1 Application of this protocol . 22 7.2.2 Types of messages for which this protocol can be used . 22 7.2.3 TAG block parameters for sentences transmitted in the datagram . 22 7.2.4 Requirements for processing incoming datagrams . 24 7.2.5 Error logging. 24 7.3 Binary image transfer using UDP multicast . 24 7.3.1 Application of this protocol . 24 SIST EN 61162-450:2011
61162-450 IEC:2011(E) – 3 – 7.3.2 Binary image structure . 25 7.3.3 Header . 25 7.3.4 Binary image descriptor structure . 27 7.3.5 Binary image data fragment . 28 7.3.6 Sender process for binary image transfer . 28 7.3.7 Receiver process for binary image transfer . 29 7.3.8 Other requirements . 30 7.3.9 Error logging. 31 8 Methods of test and required results . 32 8.1 Test set-up and equipment . 32 8.2 Basic requirements . 32 8.2.1 Equipment to be connected to the network . 32 8.2.2 Network infrastructure equipment . 32 8.3 Network function (NF) . 32 8.3.1 Maximum data rate . 32 8.3.2 Error logging function . 33 8.4 System function (SF) . 33 8.4.1 General . 33 8.4.2 Assignment of unique system function ID (SFI) . 33 8.4.3 Implementing configurable transmission groups . 33 8.5 Serial to network gateway function (SNGF) . 33 8.5.1 General . 33 8.5.2 Serial line output buffer management . 33 8.5.3 Datagram output . 34 8.6 Other network function (ONF) . 34 8.7 Low level network . 34 8.7.1 Electrical and mechanical requirements . 34 8.7.2 Network protocol . 34 8.7.3 IP address assignment for equipment . 35 8.7.4 Multicast address range . 35 8.8 Transport layer . 35 8.9 Application layer . 35 8.9.1 Application . 35 8.9.2 Datagram header . 35 8.9.3 Types of messages . 36 8.9.4 TAG block parameters . 36 8.10 Error logging . 36 8.11 Binary image transfer using UDP multicast . 37 8.11.1 Sender process test . 37 8.11.2 Receiver process test . 38 8.11.3 Image descriptor test . 38 8.11.4 Image transfer error logging . 38 Annex A (normative)
Classification of IEC 61162-1 talker identifier
mnemonics and sentences . 39 Annex B (informative)
TAG block example . 45 Annex C (normative)
Reliable transmission of command-response pair messages . 47 Annex D (informative)
Network and system design guidance . 52 Bibliography . 60 SIST EN 61162-450:2011
– 4 – 61162-450 IEC:2011(E)
Figure 1 – Network topology example . 12 Figure 2 – Ethernet frame example for a SBM
from a rate of turn sensor . 20 Figure C.1 – Command response communications . 47 Figure C.2 – State diagram . 49 Figure D.1 – General system design architecture . 52 Figure D.2 – Example of ship-shore communication architecture . 53 Figure D.3 – Security infrastructure . 54 Figure D.4 – Decoupled system . 56 Figure D.5 – Loosely coupled system . 56 Figure D.6 – Strongly coupled system . 57
Table 1 – Syslog message format . 14 Table 2 – Syslog error message codes . 14 Table 3 – Interfaces, connectors and cables . 18 Table 4 – Destination multicast addresses and port numbers . 21 Table 5 – Destination multicast addresses and port numbers for binary data transfer . 21 Table 6 – Destination multicast addresses and port numbers for other services . 21 Table 7 – Description of terms . 25 Table 8 – Binary image structure . 25 Table 9 – Header format . 26 Table 10 – Binary image descriptor format . 27 Table 11 – Examples of MIME content type for DataType codes . 28 Table 12 – Binary image data fragment format . 28 Table A.1 – Classification of IEC 61162-1 talker identifier mnemonics . 39 Table A.2 – Classification of IEC 61162-1 sentences . 41 Table B.1 – Defined parameter-codes . 46 Table D.1 – Overview of possible security functions . 55 Table D.2 – Network failure propagation possibilities . 58 SIST EN 61162-450:2011
61162-450 IEC:2011(E) – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
MARITIME NAVIGATION AND RADIOCOMMUNICATION
EQUIPMENT AND SYSTEMS –
DIGITAL INTERFACES –
Part 450: Multiple talkers and multiple listeners –
Ethernet interconnection
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 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 IEC 61162-450 has been prepared by IEC technical committee 80: Maritime navigation and radiocommunication equipment and systems. The text of this standard is based on the following documents: FDIS Report on voting 80/615/FDIS 80/621/RVD
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. SIST EN 61162-450:2011
– 6 – 61162-450 IEC:2011(E) The committee has decided that the contents of this publication will remain unchanged until the stability 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 •
transformed into an International standard, • reconfirmed, • withdrawn, • replaced by a revised edition, or • amended. A bilingual version of this publication may be issued at a later date.
SIST EN 61162-450:2011
61162-450 IEC:2011(E) – 7 – MARITIME NAVIGATION AND RADIOCOMMUNICATION
EQUIPMENT AND SYSTEMS –
DIGITAL INTERFACES –
Part 450: Multiple talkers and multiple listeners –
Ethernet interconnection
1 Scope This part of IEC 61162 specifies interface requirements and methods of test for high speed communication between shipboard navigation and radiocommunication equipment as well as between such systems and other ship systems that need to communicate with navigation and radio-communication equipment. This part of IEC 61162 is based on the application of an appropriate suite of existing international standards to provide a framework for implementing data transfer between devices on a shipboard Ethernet network. This standard provides a higher speed and higher capacity alternative to the IEC 61162-1 and IEC 61162-2 standards while retaining these standards’ basic data format. This standard provides a higher data capacity than IEC 61162-3. This standard specifies an Ethernet based bus type network where any listener may receive messages from any sender with the following properties. • This standard includes provisions for multicast distribution of information formatted according to IEC 61162-1, for example position fixes and other measurements, as well as provisions for transmission of general data blocks (binary image), for example between radar and VDR. • This standard is limited to protocols for equipment (Network nodes) connected to a single Ethernet network consisting only of OSI level one or two devices and cables (Network infrastructure). • This standard provides requirements only for equipment interfaces. By specifying protocols for transmission of IEC 61162-1 sentences and general binary image data these requirements will guarantee interoperability between equipment implementing this standard as well as a certain level of safe behaviour of the equipment itself. • This standard permits equipment using other protocols than those specified in this standard to share a network infrastructure provided that it is supplied with interfaces which satisfy the requirements described for ONF (see 4.6). • This standard does not contain any system requirements other than the ones that can be inferred from the sum of individual equipment requirements. Thus, to ascertain system properties that cannot be derived from equipment requirements alone, additional analysis or standards will be required. In particular, this applies to requirements to maintain system functionality in the face of a single point failure in equipment or networks. Informative Annex D contains guidance on how to address such issues. 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 60825-2, Safety of laser products – Part 2: Safety of optical fibre communication systems (OFCS) SIST EN 61162-450:2011
– 8 – 61162-450 IEC:2011(E) IEC 60945, Maritime navigation and radiocommunication equipment and systems – General Requirements – Methods of testing and required test results IEC 61162-1, Maritime navigation and radiocommunication equipment and systems – Digital interfaces – Part 1: Single talker and multiple listeners IEEE 802.3, IEEE Standards for Local Area Networks: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications ISOC RFC 768, User Datagram Protocol, Standard STD0006 ISOC RFC 791, Internet Protocol (IP), Standard STD0005 (and updates) ISOC RFC 792, Internet Control Message Protocol (ICMP), Standard STD0005 (and updates) ISOC RFC 826, An ethernet Address Resolution Protocol ISOC RFC 1918, Address Allocation for Private Internets, Best Current Practice BCP0005 ISOC RFC 2474, Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers ISOC RFC 5000, Internet Official Protocol Standards, Standard 0001 ISOC RFC 5227, IPv4 Address Conflict Detection ISOC RFC 5424, The Syslog Protocol NMEA 0183:2008, Standard for interfacing marine electronic devices, Version 4.00 NOTE The standards of the Internet Society (ISOC) are available on the IETF websites http://www.ietf.org. Later updates can be tracked at http://www.rfc-editor.org/rfcsearch.html 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1
ASCII printable 7 bit character encoded in one byte 3.2
binary image data block without formatting known to this protocol, i.e., non IEC 61162-1 formatted data, that can be transmitted with the protocol defined in 7.3. NOTE The term “binary image” is used to differentiate the general data transfer protocol (which may or may not be in ordinary text format) from the transmission of sentences that is always in 7
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.