SIST EN 300 940 V6.9.1:2005

• Abstract:

  CR SMG#31, TSG#7

• Status: Published
• Publication Date: 31-Jan-2005
• ICS: 33.070.01 - Mobile services in general
• Technical Committee: RES - Radio equipment and systems
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Feb-2005
• Due Date: 01-Feb-2005
• Completion Date: 01-Feb-2005
• Ref Project: ETSI EN 300 940 V6.9.1 (2000-09) - Digital cellular telecommunications system (Phase 2+) (GSM); Mobile radio interface layer 3 specification (GSM 04.08 version 6.9.1 Release 1997)

Overview

SIST EN 300 940 V6.9.1:2005 covers the Digital Cellular Telecommunications System (Phase 2+) (GSM), specifically the Mobile Radio Interface Layer 3 Specification (GSM 04.08 version 6.9.1 Release 1997). Developed by the Slovenski inštitut za standardizacijo (SIST) and harmonized with EN 300 940 by ETSI, this standard defines critical protocols and procedures for GSM mobile communications, focusing on the operation and structure of Layer 3 of the mobile radio interface.

The document is essential for industry professionals involved in mobile network equipment design, network operation, and mobile device development, ensuring interoperability and efficient operation of GSM-based cellular systems across Europe and globally.

Key Topics

• Layer 3 Protocol Architecture: Defines the structure and operation of Layer 3, responsible for managing signaling between mobile stations and the network.
• Radio Resource Management: Specifies procedures for establishing, maintaining, and releasing radio resources.
• Mobility Management: Outlines techniques for user registration, deregistration, location updating, and ensuring seamless connectivity during movement.
• Call Control and Session Management: Details the protocols for call setup, modification, and release, as well as support for supplementary services.
• Logical Channels and Message Types: Describes the use of logical channels and their role in signaling and data transfer.
• Group Call and Broadcast Services: Provides mechanisms for voice group call service (VGCS) and voice broadcast service (VBS), enhancing communication capabilities for specific user groups.
• GPRS Integration: Supports General Packet Radio Service (GPRS) for data communications, outlining relevant procedures and interactions.
• Error Handling and Abnormal Cases: Specifies standardized responses to faults, ensuring system robustness.
• Security Procedures: Includes ciphering mode settings to protect communication integrity.

Applications

SIST EN 300 940 V6.9.1:2005 is directly relevant to organizations and professionals in:

• Mobile device development: Ensures that handheld and embedded GSM-enabled equipment complies with network requirements for signaling and mobility management.
• Cellular network infrastructure: Guides the configuration of base stations, MSCs, and radio resource management platforms to support seamless mobile communication and efficient use of network resources.
• Testing and certification: Provides a baseline for interoperability tests, device compliance, and rollout of new GSM services or upgrades.
• Public safety and enterprise networks: Supports deployment of group and broadcast call services for emergencies and special organizational needs, leveraging VGCS and VBS.
• Network optimization: Assists operators in understanding procedures for handovers, paging, and handling abnormal conditions, enabling improved user experience and reliability.
• Integration with packet data services: Facilitates convergence with GPRS for data applications, necessary for evolving mobile networks.

Related Standards

For comprehensive GSM network implementation and maintenance, the following standards are closely related to SIST EN 300 940 V6.9.1:2005:

• EN 300 940: The European Norm version harmonized with SIST EN 300 940.
• ETSI TS 100 940 (GSM 04.08): Foundation for mobile radio interface Layer 3 specification.
• 3GPP TS 24.008: Continuation of GSM protocol development in 3G and beyond.
• GSM 04.07: Specifications regarding Layer 2 of the GSM radio interface.
• GSM 04.12, GSM 04.18: Detailing broadcast, group call, and additional signaling aspects.
• ETSI EN 301 511: GSM equipment requirements for harmonized operation within the EU.

Keywords: GSM standard, mobile radio interface, Layer 3 specification, digital cellular telecommunications, mobility management, radio resource management, call control, group call services, GPRS integration, ETSI GSM standards.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Digital cellular telecommunications system (Phase 2+) (GSM); Mobile radio interface layer 3 specification (GSM 04.08 version 6.9.1 Release 1997)33.070.01Mobilni servisi na splošnoMobile services in generalICS:Ta slovenski standard je istoveten z:EN 300 940 Version 6.9.1SIST EN 300 940 V6.9.1:2005en01-februar-2005SIST EN 300 940 V6.9.1:2005SLOVENSKI
STANDARD
ETSIEN300940V6.9.1(2000-09)EuropeanStandard(Telecommunicationsseries)Digitalcellulartelecommunicationssystem(Phase2+);Mobileradiointerfacelayer3specification(GSM04.08version6.9.1Release1997)GLOBALSYSTEMFORMOBILECOMMUNICATIONSRSIST EN 300 940 V6.9.1:2005

ETSI2ETSIEN300940V6.9.1(2000-09)(GSM04.08version6.9.1Release1997)ReferenceREN/TSGN-010408Q6R4KeywordsDigitalcellulartelecommunicationssystem,GlobalSystemforMobilecommunications(GSM)ETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:[phone]Fax:[phone]SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88ImportantnoticeIndividualcopiesofthepresentdocumentcanbedownloadedfrom:http://www.etsi.orgThepresentdocumentmaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.Usersofthepresentdocumentshouldbeawarethatthedocumentmaybesubjecttorevisionorchangeofstatus.InformationonthecurrentstatusofthisandotherETSIdocumentsisavailableathttp://www.etsi.org/tb/status/Ifyoufinderrorsinthepresentdocument,sendyourcommentto:[e-mail]opartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 300 940 V6.9.1:2005

ETSIETSIEN300940V6.9.1(2000-09)3(GSM04.08version6.9.1Release1997)ContentsIntellectualPropertyRights.27Foreword.27Introduction.280Scope.290.1ScopeoftheTechnicalSpecification.290.2Applicationtotheinterfacestructures.290.3Structureoflayer3procedures.290.4Testprocedures.290.5Useoflogicalchannels.300.6Overviewofcontrolprocedures.300.6.1Listofprocedures.300.7Applicabilityofimplementations.320.7.1VoiceGroupCallService(VGCS)andVoiceBroadcastService(VBS).330.7.2GeneralPacketRadioService(GPRS).331References.342Definitionsandabbreviations.372.1Randomvalues.372.2Vocabulary.383RadioResourcemanagementprocedures.393.1Overview/General.393.1.1General.393.1.2Servicesprovidedtoupperlayers.393.1.2.1Idlemode.393.1.2.2Dedicatedmode.403.1.2.3Groupreceivemode.403.1.2.4Grouptransmitmode.403.1.2.5Packetidlemode.403.1.2.6Packettransfermode.413.1.3Servicesrequiredfromdatalinkandphysicallayers.413.1.4Changeofdedicatedchannels.413.1.4.1ChangeofdedicatedchannelsusingSAPI=0.413.1.4.2ChangeofdedicatedchannelsusingotherSAPIsthan0.413.1.4.3Sequencedmessagetransferoperation.423.1.4.3.1Variablesandsequencenumbers.423.1.4.3.1.1SendstatevariableV(SD).423.1.4.3.1.2SendsequencenumberN(SD).423.1.4.3.2Proceduresfortheinitiation,transferexecutionandterminationofthesequencedmessagetransferoperation.423.1.4.3.2.1Initiation.423.1.4.3.2.2TransferExecution.423.1.4.3.2.3Termination.423.1.5ProcedureforServiceRequestandContentionResolution.423.2Idlemodeproceduresandgeneralproceduresinpacketidleandpackettransfermodes.433.2.1MobileStationside.433.2.2Networkside.443.2.2.1Systeminformationbroadcasting.443.2.2.2Paging.453.3RRconnectionestablishment.453.3.1RRconnectionestablishmentinitiatedbythemobilestation.453.3.1.1Enteringthededicatedmode:immediateassignmentprocedure.453.3.1.1.1Permissiontoaccessthenetwork.453.3.1.1.2Initiationoftheimmediateassignmentprocedure.463.3.1.1.3Answerfromthenetwork.47SIST EN 300 940 V6.9.1:2005

ETSIETSIEN300940V6.9.1(2000-09)4(GSM04.08version6.9.1Release1997)3.3.1.1.3.1OnreceiptofaCHANNELREQUESTmessage.473.3.1.1.3.2Assignmentrejection.483.3.1.1.4Assignmentcompletion.483.3.1.1.4.1Earlyclassmarksending.483.3.1.1.4.2GPRSsuspensionprocedure.493.3.1.1.5Abnormalcases.493.3.1.2Enteringthegrouptransmitmode:uplinkaccessprocedure.493.3.1.2.1Mobilestationside.503.3.1.2.1.1Uplinkinvestigationprocedure.503.3.1.2.1.2Uplinkaccessprocedure.503.3.1.2.2Networkside.513.3.1.2.3Abnormalcases.513.3.1.3DedicatedmodeandGPRS.513.3.2PagingprocedureforRRconnectionestablishment.513.3.2.1Paginginitiationbythenetwork.513.3.2.1.1PaginginitiationusingpagingsubchannelonCCCH.523.3.2.1.2PaginginitiationusingpagingsubchannelonPCCCH.533.3.2.1.3PaginginitiationusingPACCH.533.3.2.2Pagingresponse.533.3.2.3Abnormalcases.533.3.3Notificationprocedure.543.3.3.1Notificationofacall.543.3.3.2JoiningaVGCSorVBScall.543.3.3.3ReducedNCHmonitoringmechanism.553.4Proceduresindedicatedmodeandingrouptransmitmode.563.4.1SACCHprocedures.563.4.1.1General.563.4.1.2Measurementreport.573.4.1.3Extendedmeasurementreport$(MAFA)$.573.4.2Transferofmessagesandlinklayerserviceprovision.573.4.3Channelassignmentprocedure.573.4.3.1Channelassignmentinitiation.583.4.3.2Assignmentcompletion.593.4.3.3Abnormalcases.593.4.4Handoverprocedure.603.4.4.1Handoverinitiation.613.4.4.2Physicalchannelestablishment.623.4.4.2.1Finelysynchronizedcellcase.623.4.4.2.2Nonsynchronizedcellcase.623.4.4.2.3Pseudo-synchronizedcellcase.633.4.4.2.4Pre-synchronizedcellcase.633.4.4.3Handovercompletion.633.4.4.4Abnormalcases.643.4.5Frequencyredefinitionprocedure.653.4.5.1Abnormalcases.653.4.6Channelmodemodifyprocedure.653.4.6.1Normalchannelmodemodifyprocedure.653.4.6.1.1Initiationofthechannelmodemodifyprocedure.653.4.6.1.2Completionofchannelmodemodifyprocedure.663.4.6.1.3Abnormalcases.663.4.6.2Channelmodemodifyprocedureforavoicegroupcalltalker.663.4.6.2.1Initiationofthechannelmodemodifyprocedure.663.4.6.2.2Completionofmodechangeprocedure.663.4.6.2.3Abnormalcases.663.4.7Cipheringmodesettingprocedure.663.4.7.1Cipheringmodesettinginitiation.673.4.7.2Cipheringmodesettingcompletion.673.4.8Additionalchannelassignmentprocedure.673.4.8.1Additionalassignmentprocedureinitiation.683.4.8.2Additionalassignmentprocedurecompletion.683.4.8.3Abnormalcases.683.4.9Partialchannelreleaseprocedure.68SIST EN 300 940 V6.9.1:2005

ETSIETSIEN300940V6.9.1(2000-09)5(GSM04.08version6.9.1Release1997)3.4.9.1Partialreleaseprocedureinitiation.683.4.9.2Abnormalcases.683.4.10Classmarkchangeprocedure.693.4.11Classmarkinterrogationprocedure.693.4.11.1Classmarkinterrogationinitiation.693.4.11.2Classmarkinterrogationcompletion.693.4.12Indicationofnotificationsandpaginginformation.693.4.13RRconnectionreleaseprocedure.693.4.13.1Normalreleaseprocedure.693.4.13.1.1Channelreleaseprocedureinitiationindedicatedmodeandingrouptransmitmode.703.4.13.1.2Abnormalcases.713.4.13.2Radiolinkfailureindedicatedmode.713.4.13.2.1Mobileside.713.4.13.2.2Networkside.713.4.13.3RRconnectionabortionindedicatedmode.723.4.13.4Uplinkreleaseprocedureingrouptransmitmode.723.4.13.5Radiolinkfailureingrouptransmitmode.723.4.13.5.1Mobileside.723.4.13.5.2Networkside.723.4.14ReceivingaRRSTATUSmessagebyaRRentity.733.4.15Groupreceivemodeprocedures.733.4.15.1Mobilestationside.733.4.15.1.1ReceptionoftheVGCSorVBSchannel.733.4.15.1.2Monitoringofdownlinkmessagesandrelatedprocedures.733.4.15.1.2.1Spare.733.4.15.1.2.2Spare.733.4.15.1.2.3Channelmodemodifyprocedure.733.4.15.1.2.4Notificationandpaginginformation.733.4.15.1.2.4.1UseofReducedNCHmonitoring.743.4.15.1.2.5Uplinkstatusmessages.743.4.15.1.2.6Channelreleasemessage.743.4.15.1.2.7Informationonpagingchannelrestructuring.743.4.15.1.3Uplinkreplyprocedure.743.4.15.1.4Leavingthegroupreceivemode.753.4.15.1.4.1Returningtoidlemode.753.4.15.1.4.2Goingtogrouptransmitmode.753.4.15.2Networkside.753.4.15.2.1ProvisionofmessagesontheVGCSorVBSchanneldownlink.753.4.15.2.1.1General.753.4.15.2.1.2Provisionofgeneralinformationmessages.753.4.15.2.1.3Provisionofmessagesrelatedtothevoicegroupcalluplinkchannel.763.4.15.2.2ReleaseoftheVGCSorVBSChannels.763.4.15.3Failurecases.763.4.16Configurationchangeprocedure.763.4.16.1Configurationchangeinitiation.773.4.16.2Configurationchangecompletion.773.4.16.3Abnormalcases.773.4.17Mappingofuserdatasubstreamsontotimeslotsinamultislotconfiguration.773.4.18Handlingofclassmarkinformationatbandchange.783.4.19AssignmenttoaPacketDatachannel.783.4.19.1AssignmenttoPDCHinitiation.783.4.19.2CompletionoftheAssignmenttoPDCHprocedure.793.4.19.3Abnormalcases.793.4.20RR-NetworkCommandedCellChangeOrder.803.4.20.1RR-networkcommandedcellchangeorderinitiation.803.4.20.2Networkcontrolledcellreselectioncompletion.813.4.20.3Abnormalcases.813.5RRproceduresonCCCHrelatedtotemporaryblockflowestablishment.813.5.1PacketpagingprocedureusingCCCH.823.5.1.1Packetpaginginitiationbythenetwork.823.5.1.2Onreceiptofapacketpagingrequest.823.5.2PacketaccessprocedureusingCCCH.82SIST EN 300 940 V6.9.1:2005

ETSIETSIEN300940V6.9.1(2000-09)6(GSM04.08version6.9.1Release1997)3.5.2.1Enteringthepackettransfermode:packetaccessprocedure.833.5.2.1.1Permissiontoaccessthenetwork.833.5.2.1.2Initiationofthepacketaccessprocedure:channelrequest.833.5.2.1.3Packetimmediateassignment.843.5.2.1.3.1OnreceiptofaCHANNELREQUESTmessage.843.5.2.1.3.2Onephasepacketaccess.853.5.2.1.3.3Singleblockpacketaccess.853.5.2.1.3.4Packetaccessrejection.863.5.2.1.4Packetaccesscompletion.863.5.2.1.5Abnormalcases.863.5.2.2SendinganRLC/MACcontrolmessage:singleblockpacketaccessprocedure.873.5.3PacketdownlinkassignmentprocedureusingCCCH.873.5.3.1Enteringthepackettransfermode:packetdownlinkassignmentprocedure.873.5.3.1.1Void.873.5.3.1.2Initiationofthepacketdownlinkassignmentprocedure.873.5.3.1.3Packetdownlinkassignmentcompletion.893.5.3.1.4Abnormalcases.893.5.3.2SendinganRLC/MACcontrolmessage:singleblockpacketdownlinkassignmentprocedure.894ElementaryproceduresforMobilityManagement.904.1General.904.1.1MMandGMMprocedures.914.1.1.1TypesofMMandGMMprocedures.914.1.1.2MM-GMMco-ordinationforGPRSMS's.924.1.1.2.1GPRSMSoperatinginmodeAorBinanetworkthatoperatesinmodeI.924.1.1.2.2GPRSMSoperatinginmodeAorBinanetworkthatoperatesinmodeIIorIII.924.1.2MMsublayerstates.934.1.2.1MMsublayerstatesinthemobilestation.934.1.2.1.1Mainstates.934.1.2.1.2SubstatesoftheMMIDLEstate.964.1.2.2TheupdateStatus.974.1.2.3MMsublayerstatesonthenetworkside.984.1.3GPRSmobilitymanagement(GMM)sublayerstates.994.1.3.1GMMstatesintheMS.994.1.3.1.1Mainstates.994.1.3.1.1.1GMM-NULL.994.1.3.1.1.2GMM-DEREGISTERED.994.1.3.1.1.3GMM-REGISTERED-INITIATED.994.1.3.1.1.4GMM-REGISTERED.1004.1.3.1.1.5GMM-DEREGISTERED-INITIATED.1004.1.3.1.1.6GMM-ROUTING-AREA-UPDATING-INITIATED.1004.1.3.1.2SubstatesofstateGMM-DEREGISTERED.1004.1.3.1.2.1GMM-DEREGISTERED.NORMAL-SERVICE.1004.1.3.1.2.2GMM-DEREGISTERED.LIMITED-SERVICE.1004.1.3.1.2.3GMM-DEREGISTERED.ATTACH-NEEDED.1004.1.3.1.2.4GMM-DEREGISTERED.ATTEMPTING-TO-ATTACH.1004.1.3.1.2.5GMM-DEREGISTERED.NO-IMSI.1004.1.3.1.2.6GMM-DEREGISTERED.NO-CELL-AVAILABLE.1004.1.3.1.2.7GMM-DEREGISTERED.PLMN-SEARCH.1004.1.3.1.2.8GMM-DEREGISTERED.SUSPENDED.1014.1.3.1.3SubstatesofstateGMM-REGISTERED.1014.1.3.1.3.1GMM-REGISTERED.NORMAL-SERVICE.1014.1.3.1.3.2GMM-REGISTERED.SUSPENDED.1014.1.3.1.3.3GMM-REGISTERED.UPDATE-NEEDED.1014.1.3.1.3.4GMM-REGISTERED.ATTEMPTING-TO-UPDATE.1014.1.3.1.3.5GMM-REGISTERED.NO-CELL-AVAILABLE.1014.1.3.1.3.6GMM-REGISTERED.LIMITED-SERVICE.1024.1.3.1.3.7GMM-REGISTERED.ATTEMPTING-TO-UPDATE-MM.1024.1.3.1.3.8GMM-REGISTERED.IMSI-DETACH-INITIATED.1024.1.3.2GPRSupdatestatus.1024.1.3.3GMMmobilitymanagementstatesonthenetworkside.1034.1.3.3.1MainStates.103SIST EN 300 940 V6.9.1:2005

ETSIETSIEN300940V6.9.1(2000-09)7(GSM04.08version6.9.1Release1997)4.1.3.3.1.1GMM-DEREGISTERED.1034.1.3.3.1.2GMM-COMMON-PROCEDURE-INITIATED.1034.1.3.3.1.3GMM-REGISTERED.1034.1.3.3.1.4GMM-DEREGISTERED-INITIATED.1034.1.3.3.2SubstatesofstateGMM-REGISTERED.1044.1.3.3.2.1GMM-REGISTERED.NORMAL-SERVICE.1044.1.3.3.2.2GMM-REGISTERED.SUSPENDED.1044.2BehaviouroftheMSinMMIdlestate,GMM-DEREGISTEREDstateandGMM-REGISTEREDstate.1044.2.1PrimaryServiceStateselection.1054.2.1.1SelectionoftheServiceStateafterPowerOn.1054.2.1.2OtherCases.1054.2.2DetailedDescriptionoftheMSbehaviourinMMIDLEState.1064.2.2.1ServiceState,NORMALSERVICE.1064.2.2.2ServiceState,ATTEMPTINGTOUPDATE.1064.2.2.3ServiceState,LIMITEDSERVICE.1074.2.2.4ServiceState,NOIMSI.1074.2.2.5ServiceState,SEARCHFORPLMN,NORMALSERVICE.1084.2.2.6ServiceState,SEARCHFORPLMN.1084.2.2.7ServiceState,RECEIVINGGROUPCALL(NORMALSERVICE).1084.2.2.8ServiceState,RECEIVINGGROUPCALL(LIMITEDSERVICE).1094.2.3ServicestatewhenbacktostateMMIDLEfromanotherstate.1094.2.4BehaviourinstateGMM-DEREGISTERED.1104.2.4.1Primarysubstateselection.1104.2.4.1.1SelectionofthesubstateafterpoweronorenablingtheMS'sGPRScapability.1104.2.4.1.2OtherCases.1104.2.4.2DetaileddescriptionoftheMSbehaviourinstateGMM-DEREGISTERED.1114.2.4.2.1Substate,NORMAL-SERVICE.1114.2.4.2.2Substate,ATTEMPTING-TO-ATTACH.1114.2.4.2.3Substate,LIMITED-SERVICE.1114.2.4.2.4Substate,NO-IMSI.1114.2.4.2.5Substate,NO-CELL.1114.2.4.2.6Substate,PLMN-SEARCH.1124.2.4.2.7Substate,ATTACH-NEEDED.1124.2.4.2.8Substate,SUSPENDED.1124.2.4.3SubstatewhenbacktostateGMM-DEREGISTEREDfromanotherGMMstate.1124.2.5BehaviourinstateGMM-REGISTERED.1124.2.5.1DetaileddescriptionoftheMSbehaviourinstateGMM-REGISTERED.1134.2.5.1.1Substate,NORMAL-SERVICE.1134.2.5.1.2Substate,SUSPENDED.1134.2.5.1.3Substate,UPDATE-NEEDED.1134.2.5.1.4Substate,ATTEMPTING-TO-UPDATE.1134.2.5.1.5Substate,NO-CELL-AVAILABLE.1134.2.5.1.6Substate,LIMITED-SERVICE.1144.2.5.1.7Substate,ATTEMPTING-TO-UPDATE-MM.1144.3MMcommonprocedures.1144.3.1TMSIreallocationprocedure.1144.3.1.1TMSIreallocationinitiationbythenetwork.1144.3.1.2TMSIreallocationcompletionbythemobilestation.1154.3.1.3TMSIreallocationcompletioninthenetwork.1154.3.1.4Abnormalcases.1154.3.2Authenticationprocedure.1164.3.2.1Authenticationrequestbythenetwork.1164.3.2.2Authenticationresponsebythemobilestation.1164.3.2.3Authenticationprocessinginthenetwork.1164.3.2.4Cipheringkeysequencenumber.1164.3.2.5Unsuccessfulauthentication.1164.3.2.6Abnormalcases.1174.3.3Identificationprocedure.1174.3.3.1Identityrequestbythenetwork.1174.3.3.2Identificationresponsebythemobilestation.1184.3.3.3Abnormalcases.1184.3.4IMSIdetachprocedure.118SIST EN 300 940 V6.9.1:2005

ETSIETSIEN300940V6.9.1(2000-09)8(GSM04.08version6.9.1Release1997)4.3.4.1IMSIdetachinitiationbythemobilestation.1184.3.4.2IMSIdetachprocedureinthenetwork.1194.3.4.3IMSIdetachcompletionbythemobilestation.1194.3.4.4Abnormalcases.1194.3.5Abortprocedure.1194.3.5.1Abortprocedureinitiationbythenetwork.1194.3.5.2Abortprocedureinthemobilestatio
...