ETSI ETS 300 902 ed.1 (1997-04)
Digital cellular telecommunications system (Phase 2+) (GSM); Technical realization of Short Message Service Cell Broadcast (SMSCB) (GSM 03.41 version 5.4.1)
Digital cellular telecommunications system (Phase 2+) (GSM); Technical realization of Short Message Service Cell Broadcast (SMSCB) (GSM 03.41 version 5.4.1)
DE/SMG-040341QR3
Digitalni celični telekomunikacijski sistem (faza 2+) – Tehnična realizacija storitve kratkih sporočil (SMS) – Izvedba s celično radiodifuzijo (SMSCB) (GSM 03.41, različica 5.4.1)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ETS 300 902 E1:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±7HKQLþQDUHDOL]DFLMDVWRULWYH
NUDWNLKVSRURþLO606±,]YHGEDVFHOLþQRUDGLRGLIX]LMR606&%*60
UD]OLþLFD
Digital cellular telecommunications system (Phase 2+) (GSM); Technical realization of
Short Message Service Cell Broadcast (SMSCB) (GSM 03.41 version 5.4.1)
Ta slovenski standard je istoveten z: ETS 300 902 Edition 1
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 902 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ETS 300 902 E1:2003
---------------------- Page: 2 ----------------------
SIST ETS 300 902 E1:2003
EUROPEAN ETS 300 902
TELECOMMUNICATION April 1997
STANDARD
Source: ETSI TC-SMG Reference: DE/SMG-040341QR3
ICS: 33.020
Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
Digital cellular telecommunications system (Phase 2+);
Technical realization of Short Message Service (SMS);
Cell Broadcast (SMSCB)
(GSM 03.41 version 5.4.1)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.
---------------------- Page: 3 ----------------------
SIST ETS 300 902 E1:2003
Page 2
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.
---------------------- Page: 4 ----------------------
SIST ETS 300 902 E1:2003
Page 3
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
Contents
Foreword .5
1 Scope .7
1.1 Normative references .7
1.2 Abbreviations .7
2 General description .8
3 Network Architecture.9
4 CBE Functionality.9
5 CBC Functionality.9
6 BSC Functionality.10
7 BTS Functionality .10
8 MS Functionality.10
9 Protocols and Protocol Architecture.11
9.1 CBC-BSC Primitives .13
9.1.1 Identification of a message .13
9.1.2 WRITE-REPLACE Request/Indication.14
9.1.3 KILL Request/Indication .15
9.1.4 REPORT Response/Confirm .15
9.1.5 STATUS-CBCH-QUERY Request/Indication.15
9.1.6 STATUS-CBCH-QUERY Response/Confirm.15
9.1.7 STATUS-MESSAGE-QUERY Request/Indication .16
9.1.8 STATUS-MESSAGE-QUERY Response/Confirm .16
9.1.9 REJECT Response/Confirm .16
9.1.10 RESTART-INDICATION Request/Indication.16
9.1.11 RESET Request/Indication.17
9.1.12 FAILURE-INDICATION Request/Indication .17
9.1.13 SET-DRX Request/Indication.17
9.1.14 SET-DRX- REPORT Response/Confirm .18
9.2 Parameters .18
9.2.1 Message-Identifier.18
9.2.2 Old-Serial-Number .18
9.2.3 New-Serial-Number.18
9.2.4 Number-of-Pages.18
9.2.5 Cell-List .18
9.2.6 Channel Indicator .18
9.2.7 Category.18
9.2.8 Repetition-Rate .19
9.2.9 No-of-Broadcasts-Requested.19
9.2.10 No-of-Broadcasts-Completed-List.19
9.2.11 Cell-Identifier .19
9.2.12 Schedule-Period.20
9.2.13 Reserved-Slots.20
9.2.14 Failure-List.20
9.2.15 CBCH-Loading-List .20
9.2.16 Cause .21
9.2.17 Diagnostic.21
9.2.18 Data Coding Scheme .21
9.2.19 CBS-Message-Information-Page n .21
---------------------- Page: 5 ----------------------
SIST ETS 300 902 E1:2003
Page 4
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
9.2.20 CBS-Message-Information-Length n . 21
9.2.21 Recovery-Indication . 22
9.3 Message Format on BTS-MS Interface . 22
9.3.1 General Description. 22
9.3.2 Message Content. 22
10 SMSCB Index . 25
Annex A (informative): Protocols for interconnecting CBC and BSC . 27
History. 28
---------------------- Page: 6 ----------------------
SIST ETS 300 902 E1:2003
Page 5
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) Technical Committee (TC) of the European Telecommunications Standards Institute (ETSI).
This ETS defines the Cell Broadcast short message service (CBS). It defines the primitives over the Cell
Broadcast Centre - Base Station System (CBC-BSS) interface and the message formats over the Base
Station System - Mobile Station (BSS-MS) interface for Teleservice 23 within the digital cellular
telecommunications system (Phase 2+).
This ETS is a GSM technical specification version 5, which incorporates GSM Phase 2+
enhancements/features to the version 4 GSM technical specification. The ETS from which this Phase 2+
ETS has evolved is Phase 2 GSM ETS 300 537 Edition 2 (GSM 03.41 version 4.11.0).
The contents of this ETS is subject to continuing work within TC-SMG and may change following formal
TC-SMG approval. Should TC-SMG modify the contents of this ETS, it will be resubmitted for OAP by
ETSI with an identifying change of release date and an increase in version number as follows:
Version 5.x.y
where:
y the third digit is incremented when editorial only changes have been incorporated in the
specification;
x the second digit is incremented for all other types of changes, i.e. technical enhancements,
corrections, updates, etc.
Transposition dates
Date of adoption: 21 March 1997
Date of latest announcement of this ETS (doa): 31 July 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 January 1998
Date of withdrawal of any conflicting National Standard (dow): 31 January 1998
---------------------- Page: 7 ----------------------
SIST ETS 300 902 E1:2003
Page 6
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
Blank page
---------------------- Page: 8 ----------------------
SIST ETS 300 902 E1:2003
Page 7
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
1 Scope
This European Telecommunication Standard (ETS) describes the Cell Broadcast short message service
(CBS). It defines the primitives over the Cell Broadcast Centre - Base Station System (CBC-BSS)
interface and the message formats over the Base Station System - Mobile Station (BSS-MS) interface for
Teleservice 23 as specified in GSM 02.03 [2].
1.1 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references, the
latest edition of the publication referred to applies.
[1] GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+);
Abbreviations and acronyms".
[2] GSM 02.03 (ETS 300 905): "Digital cellular telecommunications system
(Phase 2+); Teleservices supported by a GSM Public Land Mobile Network
(PLMN)".
[3] GSM 03.38 (ETS 300 900): "Digital cellular telecommunications system
(Phase 2+); Alphabets and language-specific information".
[4] GSM 03.40 (ETS 300 901): "Digital cellular telecommunications system
(Phase 2+); Technical realization of the Short Message Service (SMS)
Point-to-Point (PP)".
[5] GSM 03.47 (ETR 354): "Digital cellular telecommunications system; Example
protocol stacks for interconnecting Service Centre(s) (SC) and Mobile-services
Switching Centre(s) (MSC)".
[6] GSM 03.49: "Digital cellular telecommunications system (Phase 2+); Example
protocol stacks for interconnecting Cell Broadcast Centre (CBC) and Base
Station Controller (BSC)".
[7] GSM 04.12 (ETS 300 943): "Digital cellular telecommunications system
(Phase 2+); Short Message Service Cell Broadcast (SMSCB) support on the
mobile radio interface".
[8] GSM 05.02 (ETS 300 908): "Digital cellular telecommunications system
(Phase 2+); Multiplexing and multiple access on the radio path".
[9] GSM 07.05: "Digital cellular telecommunications system (Phase 2+); Use of
Data Terminal Equipment - Data Circuit terminating Equipment (DTE - DCE)
interface for Short Message Service (SMS) and Cell Broadcast Service (CBS)".
[10] GSM 08.52: "Digital cellular telecommunications system; Base Station Controller
- Base Transceiver Station (BSC - BTS) interface Interface principles".
[11] GSM 08.58: "Digital cellular telecommunications system (Phase 2+); Base
Station Controller - Base Transceiver Station (BSC - BTS) interface Layer 3
specification".
[12] CCITT Recommendation X.210: "Open systems interconnection layer service
definition conventions".
1.2 Abbreviations
Abbreviations used in this ETS are listed in GSM 01.04 [1].
---------------------- Page: 9 ----------------------
SIST ETS 300 902 E1:2003
Page 8
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
2 General description
The CBS service is analogous to the Teletex service offered on television, in that like Teletex, it permits a
number of unacknowledged general messages to be broadcast to all receivers within a particular region.
CBS messages are broadcast to defined geographical areas known as cell broadcast areas. These areas
may comprise of one or more cells, or may comprise the entire PLMN. Individual CBS messages will be
assigned their own geographical coverage areas by mutual agreement between the information provider
and the PLMN operator. CBS messages may originate from a number of Cell Broadcast Entities (CBEs),
which are connected to the Cell Broadcast Centre. CBS messages are then sent from the CBC to the
BTSs, in accordance with the CBS's coverage requirements.
The CBS message comprises of 82 octets, which, using the default character set, equates to
93 characters. Up to 15 of these messages (pages) may be concatenated to form a macromessage. Each
page of such macromessages will have the same message identifier (indicating the source of the
message), and the same serial number. Using this information, the MS is able to identify and ignore
re-broadcasts of already received messages.
CBS messages are broadcast cyclically by the BTS at a frequency and for a duration specified by the
information provider. The frequency at which messages are repeatedly transmitted will be dependent on
the information that they contain; for example, it is likely that dynamic information such as road traffic
information, will require more frequent transmission than weather information. The repetition rate will also
be affected by the desire for messages to be received by high speed mobiles which rapidly traverse cells.
All suitably equipped mobiles within the catchment area of the transmitting BTS will be able to receive the
broadcast messages, provided that they are switched on and in the idle state.
CBS messages may be broadcast on two different cell broadcast channels, which are characterized by
different QoS. A MS is always able to read the basic channel (see [8]). The reading of the extended
channel may collide with other tasks of the MS. Therefore the probability of receiving a CBS message on
the extended channel is smaller than on the basic channel. The reading of the extended channel for MSs
is optional. The scheduling on the channels will be done independently.
To permit mobiles to selectively display only those messages required by the MS user, CBS messages
are assigned a message class which categorises the type of information that they contain and the
language in which the message has been compiled. Through the use of appropriate MMI, the user is then
able to ignore message types that he does not wish to receive, e.g. advertising information or messages
in an unfamiliar language.
---------------------- Page: 10 ----------------------
SIST ETS 300 902 E1:2003
Page 9
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
3 Network Architecture
The basic network structure of CBS is depicted by figure 1.
outside scope of GSM Specs. inside scope of GSM Specs.
BTSs
3 4
MSs
1 3 4
CBE
2 MSs
BSC
CBC 3 4
MSs
CBE 1 2
2
Figure 1
- message transfer on link 1 is outside the scope of GSM Specifications;
- message transfer on link 2 is described in subclause 9.1;
- message transfer on link 3 is described in GSM 08.58;
- message transfer on link 4 is described in GSM 04.12 and the timing of messages transferred on
link 4 is described in GSM 05.02.
4 CBE Functionality
The functionality of the CBE is outside of the scope of GSM Specifications; however it is assumed that the
CBE is responsible for all aspects of formatting CBS, including the splitting of a CBS message into a
number of pages.
5 CBC Functionality
As the CBC (and any originating point for cell broadcast short messages) is regarded as a node outside
the PLMN, only the requirements placed upon the CBC by CBS functionality are specified by this ETS.
The CBC may be connected to several BSCs. The CBC may be connected to several CBEs. The CBC
shall be responsible for the management of cell broadcast short messages including:
- allocation of serial numbers;
- modifying or deleting messages held by the BSC;
- initiating broadcast by sending fixed length cell broadcast short messages to a BSC for each
language provided by the cell, and where necessary padding the message with the appropriate
character to a length of 82 octets;
- determining the set of cells/BTSs to which a message should be broadcast, and indicating within
the Serial Number the geographical scope of each message;
- determining the time at which a message should commence being broadcast;
- determining the time at which a message should cease being broadcast and subsequently
instructing each BSC to cease broadcast of the message;
---------------------- Page: 11 ----------------------
SIST ETS 300 902 E1:2003
Page 10
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
- determining the rate at which broadcast of the message should be repeated;
- determining the cell broadcast channel, on which the message should be broadcast.
To work efficiently on the interfaces, the BSC - which is normally controlling more than one cell of a
broadcast area - should be used as a concentrator as far as CB message handling is concerned. Hence,
the CBC should work on lists of cells when issuing CB related requests towards the BSC.
6 BSC Functionality
The BSC shall interface to only one CBC. A BSC may interface to several BTSs as indicated by
GSM 08.52. The BSC shall be responsible for:
- interpretation of commands from the CBC;
- storage of cell broadcast messages;
- scheduling of cell broadcast messages on the CBCH;
- providing an indication to the CBC when the desired repetition rate cannot be achieved;
- providing to the CBC acknowledgement of successful execution of commands received from the
CBC;
- reporting to the CBC failure when a command received from the CBC is not understood or cannot
be executed;
- routing cell broadcast messages to the appropriate BTSs;
- transferring CBS information to each appropriate BTS via a sequence of 4 SMS BROADCAST
REQUEST messages or 1 SMS BROADCAST COMMAND message (see GSM 08.58), indicating
the channel which shall be used;
- optionally generating Schedule Messages, indicating the intended schedule of transmissions (see
GSM 04.12);
- optionally receiving CBCH Load Indication messages and reacting by broadcasting a burst of
scheduled SMSCB messages or by suspending the broadcast for a period indicated by BTS (see
GSM 08.58).
To work efficiently on the interfaces, the BSC should forward CB related messages to the CBC using cell
lists as far as applicable.
7 BTS Functionality
The BTS is responsible for conveying CBS information received via SMS BROADCAST REQUEST or
SMS BROADCAST COMMAND messages over the radio path to the MS:
- Optionally generating CBCH Load Indication messages, indicating an underflow or overflow
situation on the CBCH (see GSM 08.58).
8 MS Functionality
The MS is responsible for recombination of the blocks received via the radio path to reconstitute the cell
broadcast short message. The precise method of display of cell broadcast short messages is outside the
scope of GSM Specifications, however it is assumed that an MS will:
- discard sequences transferred via the radio path (see GSM 04.12) which do not consist of
consecutive blocks;
- have the ability to discard CBS information which is not in a suitable data coding scheme;
---------------------- Page: 12 ----------------------
SIST ETS 300 902 E1:2003
Page 11
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
- have the ability to discard a message which has a message identifier indicating that it is of subject
matter which is not of interest to the MS;
- have the ability to ignore repeat broadcasts of messages already received (message has not
changed since it was last broadcast i.e. sequence number has not changed within the message's
indicated geographical area);
- have the ability to transfer a message via the R interface when the R interface is supported;
- optionally enter SMSCB DRX mode based upon received Schedule Messages (see GSM 04.12);
- optionally skip reception of the remaining block(s) of a cell broadcast message which do(es) not
contain cell broadcast information (see GSM 04.12);
- optionally read the extended channel.
9 Protocols and Protocol Architecture
Commands interpreted by the BSC will result in a sequence of 4 SMS BROADCAST REQUEST
messages or 1 SMS BROADCAST COMMAND message being sent to a BTS, which in turn result in a
sequence of 4 messages being transferred via the BTS-MS interface (see GSM 04.12).
With the SMS BROADCAST REQUEST mode of operation, the 88 octet fixed length CBS page which is
specified in subclause 9.3 is split into four 22 octet blocks which are carried in SMS BROADCAST
REQUEST messages as follows:
st
octets 1-22 are transferred in the 1 SMS BROADCAST REQUEST
with a sequence number (see GSM 04.12) indicating first block;
nd
octets 23-44 are transferred in the 2 SMS BROADCAST REQUEST
with a sequence number (see GSM 04.12) indicating second block;
rd
octets 45-66 are transferred in the 3 SMS BROADCAST REQUEST
with a sequence number (see GSM 04.12) indicating third block;
th
octets 67-88 are transferred in the 4 SMS BROADCAST REQUEST
with a sequence number (see GSM 04.12) indicating fourth block.
Figure 2 illustrates the protocol architecture and the scope of the various GSM Specifications for the SMS
BROADCAST REQUEST mode of operation.
---------------------- Page: 13 ----------------------
SIST ETS 300 902 E1:2003
Page 12
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
GSM 03.41
GSM 03.41 Subclause 9.3
Subclause 9.1
GSM 08.58 GSM 04.12
CBC BSC BTS MSs
Write-Replace
SMS BROADCAST REQUEST 1
1
Report-Success
SMS BROADCAST REQUEST 2
2
SMS BROADCAST REQUEST 3
3
SMS BROADCAST REQUEST 4
4
Figure 2
With the SMS BROADCAST COMMAND mode of operation, the BSC sends to the BTS in one single
message the 88 octet fixed length CBS page. The BTS then splits the page into four 22 octet blocks, adds
the sequence number (see GSM 04.12) and transmits the four resulting blocks on the air.
Figure 3 illustrates the protocol architecture and the scope of the various GSM Specifications for the SMS
BROADCAST COMMAND mode of operation.
---------------------- Page: 14 ----------------------
SIST ETS 300 902 E1:2003
Page 13
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
GSM 03.41
GSM 03.41 Subclause 9.3
Subclause 9.1
GSM 08.58 GSM 04.12
CBC BSC BTS MSs
Write-Replace
SMS BROADCAST COMMAND
1
Report-Success
2
3
4
Figure 3
9.1 CBC-BSC Primitives
The term primitive is used to indicate "an abstract, implementation independent interaction between a
service user and a service provider" (see CCITT X.210). For the CBC-BSC interface, the service provider
would be the protocol interconnecting CBC and BSC. A Primitive may therefore be viewed as an abstract,
implementation independent request/indication or response/confirm interaction between the service user
(CBC or BSC) and the service provider (protocol). A set of primitives for use between the CBC and BSC is
specified appropriate to the functionality assigned to the CBC and BSC in clauses 5 and 6. No mandatory
protocol between the CBC and the BSC is specified by GSM, this is a matter of agreement between CBC
and PLMN operators. GSM 03.49 (see also annex A of this ETS) provides example protocol stacks using
the primitives defined as follows.
NOTE: In the following definitions, M indicates "mandatory parameter" and O indicates
"optional parameter".
9.1.1 Identification of a message
Within a CBC-BSC interface, a message is uniquely identified by the quartet (message_identifier,
serial_number, Cell Identifier, Channel Indicator). This means that even when two messages have the
same semantic contents (for example the same weather forecast) but in different languages or coding
schemes, they are considered as different and must therefore be identified by a different quartet.
The serial number is managed cyclically and therefore this does not prevent to re-use the same quartet for
a different message when the serial number have been incremented a sufficient number of times. How to
manage the ambiguity is described here-after.
This unique identification of a message across the CBC-BSC interface is used in all the primitive defined
hereafter. This means that the quartet will be implicitly or explicitly present in every interface primitive
which applies to a given message.
This unique quartet will be referred in the rest of the document as the "message reference".
---------------------- Page: 15 ----------------------
SIST ETS 300 902 E1:2003
Page 14
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
9.1.2 WRITE-REPLACE Request/Indication
Parameter Reference Presence
Message-Identifier 9.2.1 M
Old-Serial-Number 9.2.2 O
New-Serial-Number 9.2.3 M
Cell-List 9.2.5 M
Channel Indicator 9.2.6 O
Category 9.2.6 O
Repetition-Rate 9.2.7 M
No-of-Broadcasts-Requested 9.2.8 M
Number-of-Pages 9.2.4 M
Data Coding Scheme 9.2.17 M
CBS-Message-Information-Page 1 9.2.18 M
CBS-Message-Information-Length 1 9.2.19 M
CBS-Message-Information-Page 2 9.2.18 O
CBS-Message-Information-Length 2 9.2.19 O
::
CBS-Message-Information-Page n 9.2.18 O
CBS-Message-Information-Length n 9.2.19 O
This primitive is sent by the CBC to the BSC. The CBC will use this primitive to either cause a new
message to be broadcast or to change a message currently being broadcast.
If no old serial number is present then the primitive will be interpreted by the BSC as an instruction to
broadcast a new message in all the cells of the Cell list and on the channel derived by the Channel
Indicator (see the clause on parameters that describes the implicit value of the Channel Indicator when
not present in the message). The BSC will build as many message references as the number of cells in
the list. These message references will be used in particular in the subsequent write_replace and kill
primitives.
If an old serial number is present, then the primitive will cause all information currently associated with the
combination of message identifier, serial number, Channel Indicator and the list of cells in the Cell list to
be deleted from the cells in the BSC (i.e. for all cells provided in the Cell-List parameter) and be replaced
by information conveyed in the primitive.
All cells which should perform the broadcasting are mentioned in the Cell-List parameter.
The broadcast of the referenced message in the cells which are not mentioned in the Cell-List remains
unaffected. The BSC will build as many message references as the number of cells in the list. These
references will be used in particular in the subsequent write_replace and kill primitives.
When a message reference is derived from a primitive without any old serial number (write primitive) and
the message reference is already known by the BSC for certain cells in the list, the primitive will be
rejected with the cause "message reference already used". The list of cells where the message reference
is not valid will be provided in the REPORT message.
If no category is present, the default category is interpreted by the BSC, see the parameter clause.
This primitive is responded by a REPORT or REJECT primitive.
NOTE: In the case of multipage messages, the individual pages are considered as
independent by the BSC scheduling algorithm.
---------------------- Page: 16 ----------------------
SIST ETS 300 902 E1:2003
Page 15
ETS 300 902 (GSM 03.41 version 5.4.1): April 1997
9.1.3 KILL Request/Indication
Parameter Reference Presence
Message-Identifier
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.