Link to this pageThe first Addendum of the IFC4 release has the main scope to provide documentation improvements, resolve issues that had occurred since the official release of IFC4 in March 2013, and to addresses implementation issues and concerns.
The main change incorporated into IFC4 ADD1 schema is:
\\\* Improvement and simplification of the explicit geometric representation of composite curves: addition of a new geometric item for indexed based poly curves. It requires the addition of the following entities and types: \\\* entities IfcIndexedPolyCurve, IfcCartesianPointList2D \\\* select type IfcSegmentIndexSelect \\\* defined types IfcArcIndex, IfcLineIndex
Minor corrections and improvements to the IFC4 ADD1 schema include:
\\\* Use of defined types throughout the schema, i.e. using IfcInteger instead of <eminteger, including="" the="" addition="" of="" ifcbinary="" *="" use="" of="" the="" new="" type="" ifcpositiveinteger="" to="" restrict="" the="" indices="" used="" e.g.="" for="" tessellated="" items="" to="" positive,="" one-based="" integers="" *="" adding="" the="" missing="" attribute="" longname="" to="" ifcbuildingsystem="" in="" order="" to="" make="" it="" consistent="" with="" ifcdistributionsystem.="" *="" promoting="" the="" inverse="" attribute="" hascoverings="" from="" ifcbuildingelement="" to="" ifcelement="" to="" enable="" the="" inverse="" navigation="" also="" for="" ifcdistributionelement="" *="" adding="" the="" inverse="" attribute="" hascoordinateoperation="" to="" ifcgeometricrepresentationsystem="" and="" ifccoordinatereferencesystem="" to="" enable="" the="" inverse="" navigation="" to="" the="" gis="" coordinate="" transformation="" *="" making="" the="" indespensible="" name="" attribute="" mandatory="" at="" ifccoordinatereferencesystem="" while="" making="" the="" geodeticdatum="" optional="" *="" changing="" the="" cardinality="" of="" the="" inverse="" attribute="" definesoccurrence="" at="" ifcpropertysetdefinition="" to="" allow="" property="" sets="" to="" be="" shared="" by="" many="" such="" relationships="" *="" adding="" the="" where="" rule="" nocoordoperation="" to="" ifcgeometricrepresentationsubcontext="" to="" prevent="" the="" use="" of="" conflicting="" gis="" transformations="" of="" sub="" contexts="" *="" adding="" the="" where="" rule="" unboundedsurface="" to="" ifcboxedhalfspace="" to="" prevent="" the="" use="" of="" bounded="" surfaces="" as="" clipping="" planes="" *="" adding="" the="" where="" rule="" uniquepropertysetnames="" at="" ifcobject="" and="" ifctypeobject="" to="" enforce="" property="" sets="" attached="" to="" a="" single="" object="" to="" have="" unique="" names="" *="" remove="" the="" where="" rule="" hasownerhistory="" at="" ifcproject="" to="" enable="" model="" views="" not="" using="" owner="" history="" information="" *="" remove="" the="" where="" rule="" correctshapedecomposition="" at="" ifcramp,="" ifcroof,="" ifcstair="" to="" enable="" model="" views="" to="" determine="" correct="" use="" of="" geometric="" shape="" representations="" including="" the="" addition="" of="" ifcbinary="" *="" use="" of="" the="" new="" type="" ifcpositiveinteger="" to="" restrict="" the="" indices="" used="" e.g.="" for="" tessellated="" items="" to="" positive,="" one-based="" integers="" *="" adding="" the="" missing="" attribute="" longname="" to="" ifcbuildingsystem="" in="" order="" to="" make="" it="" consistent="" with="" ifcdistributionsystem.="" *="" promoting="" the="" inverse="" attribute="" hascoverings="" from="" ifcbuildingelement="" to="" ifcelement="" to="" enable="" the="" inverse="" navigation="" also="" for="" ifcdistributionelement="" *="" adding="" the="" inverse="" attribute="" hascoordinateoperation="" to="" ifcgeometricrepresentationsystem="" and="" ifccoordinatereferencesystem="" to="" enable="" the="" inverse="" navigation="" to="" the="" gis="" coordinate="" transformation="" *="" making="" the="" indespensible="" name="" attribute="" mandatory="" at="" ifccoordinatereferencesystem="" while="" making="" the="" geodeticdatum="" optional="" *="" changing="" the="" cardinality="" of="" the="" inverse="" attribute="" definesoccurrence="" at="" ifcpropertysetdefinition="" to="" allow="" property="" sets="" to="" be="" shared="" by="" many="" such="" relationships="" *="" adding="" the="" where="" rule="" nocoordoperation="" to="" ifcgeometricrepresentationsubcontext="" to="" prevent="" the="" use="" of="" conflicting="" gis="" transformations="" of="" sub="" contexts="" *="" adding="" the="" where="" rule="" unboundedsurface="" to="" ifcboxedhalfspace="" to="" prevent="" the="" use="" of="" bounded="" surfaces="" as="" clipping="" planes="" *="" adding="" the="" where="" rule="" uniquepropertysetnames="" at="" ifcobject="" and="" ifctypeobject="" to="" enforce="" property="" sets="" attached="" to="" a="" single="" object="" to="" have="" unique="" names="" *="" remove="" the="" where="" rule="" hasownerhistory="" at="" ifcproject="" to="" enable="" model="" views="" not="" using="" owner="" history="" information="" *="" remove="" the="" where="" rule="" correctshapedecomposition="" at="" ifcramp,="" ifcroof,="" ifcstair="" to="" enable="" model="" views="" to="" determine="" correct="" use="" of="" geometric="" shape=""></eminteger,>