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编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第PAGE12页共NUMPAGES12页第PAGE\*MERGEFORMAT12页共NUMPAGES\*MERGEFORMAT12页Chapter10UsingBlockandExternalReferences10.1OverviewAutoCADprovidesseveralfeaturestohelpyoumanageobjectsinyourdrawings.Withblocksyoucanorganizeandmanipulatemanyobjectsasonecomponent.Youcanalsoassociateitemsofinformationwiththeblocksinyourdrawings-forexample,partnumbersandprices-byattachingattributes.Specificationsheetsorbillsofmaterialscanbecreatedusingthisinformation.YoucanattachoroverlayentiredrawingsinyourcurrentdrawingbyusingAutoCADexternalreferences,orxrefs.Whenyouopenadrawingthatcontainsxrefs,anychangesthathavebeenmadeinthereferenceddrawingappearinthecurrentdrawing.10.2WorkingwithBlocksAblockisacollectionofobjectsyoucanassociatetogethertoformasingleobject,orblockdefinition.Youcaninsert,scale,androtateablockinadrawing.Youcanexplodeablockintoitscomponentobjects,modifythem,andredefinetheblock.AutoCADupdatesallcurrentandfutureinstancesofthatblockbasedontheblockdefinition.Blocksstreamlinethedrawingprocess.Forexample,youcanuseblockstoBuildastandardlibraryoffrequentlyusedsymbols,components,orstandardparts.Youcaninsertthesameblocknumeroustimesinsteadofre-creatingthedrawingelementseachtime.Revisedrawingsefficientlybyinserting,relocating,andcopyingblocksascomponentsratherthanindividualgeometricobjects.Savediskspacebystoringallreferencestothesameblockasoneblockdefinitioninthedrawingdatabase.Forinformationabouthowtocreateablock,see"DefiningBlocks."Whenyouinsertablockinyourdrawing,youarecreatingablockinstance.Eachtimeyouinsertablockinstance,youassignascalefactorandrotationangletotheinsertedblock.Youcanalsoscaleablockinstanceusingdifferentvaluesinanycoordinate(X,Y,Z)direction.Blocksmakeitpossibleforyoutoorganizeyourdrawingtasksinasystematicway,sothatyoucansetup,redesign,andsorttheobjectsinyourdrawingsandtheinformationassociatedwiththem.DefiningBlocksYoucangroupobjectstocreateblockdefinitionsinthecurrentdrawing,oryoucansavetheblockasas
