ITIRBSDRADNATSHNOCOPYINGWITHOUTBSIPERMISSIONEXCEPTASPERMITTEDBYCOPYRIGHTLAWBSI389ChiswickHighRoadLondonW44ALBSI—BritishStandardsInstitutionBSIistheindependentnationalbodyresponsibleforpreparingBritishStandards.ItpresentstheUKviewonstandardsinEuropeandattheinternationallevel.ItisincorporatedbyRoyalCharter.RevisionsBritishStandardsareupdatedbyamendmentorrevision.UsersofBritishStandardsshouldmakesurethattheypossessthelatestamendmentsoreditions.ItistheconstantaimofBSItoimprovethequalityofourproductsandservices.WewouldbegratefulifanyonefindinganinaccuracyorambiguitywhileusingthisBritishStandardwouldinformtheSecretaryofthetechnicalcommitteeresponsible,theidentityofwhichcanbefoundontheinsidefrontcover.Tel:+44(0)2089969000.Fax:+44(0)2089967400.BSIoffersmembersanindividualupdatingservicecalledPLUSwhichensuresthatsubscribersautomaticallyreceivethelatesteditionsofstandards.BuyingstandardsOrdersforallBSI,internationalandforeignstandardspublicationsshouldbeaddressedtoCustomerServices.Tel:+44(0)2089969001.Fax:+44(0)2089967001.Email:orders@bsi-global.com.StandardsarealsoavailablefromtheBSIwebsiteat:+44(0)2089967111.Fax:+44(0)2089967048.Email:info@bsi-global.com.SubscribingmembersofBSIarekeptuptodatewithstandardsdevelopmentsandreceivesubstantialdiscountsonthepurchasepriceofstandards.FordetailsoftheseandotherbenefitscontactMembershipAdministration.Tel:+44(0)2089967002.Fax:+44(0)2089967001.Email:membership@bsi-global.com.InformationregardingonlineaccesstoBritishStandardsviaBritishStandardsOnlinecanbefoundat://–electronic,photocopying,recordingorotherwise–withoutpriorwrittenpermissionfromBSI.Thisdoesnotprecludethefreeuse,inthecourseofimplementingthestandard,ofnecessarydetailssuchassymbols,andsize,typeorgradedesignations.IfthesedetailsaretobeusedforanyotherpurposethanimplementationthenthepriorwrittenpermissionofBSImustbeobtained.DetailsandadvicecanbeobtainedfromtheCopyright&LicensingManager.Tel:+44(0)2089967070.Fax:+44(0)2089967553.Email:copyright@bsi-global.com.