Overview on Implementer Agreements

The IFC specification is meant to be neutral to the application types and exchange scenarios by offering a general protocol for the building industry. It therefore has to be generic by nature and has to provide often several alternatives to model building elements, properties, shape and geometry. In addition, like each exchange specification, also the IFC specification has a certain level of ambiguity.

Too many alternatives however make the implementation more complex. By restricting the alternatives for the implementation a faster and more reliable implementation can be achieved. The data exchange between different application can also be more use case driven if the implementation adheres to view definitions and corresponding implementer agreements.

• view definition (or model view definition - MVD) define a subset of the IFC standard to be implemented for a certain exchange scenario
• implementer agreements define additional restrictions and common agreements on using particular attributes (or values), geometric representation types or relationships in order to speed-up implementation, while maintaining the same scope of the view definition

• This site is currently used to publish the implementer agreements for the IFC extended coordination view.

Therefore it is important to define agreements in the group of implementers on how the specification has to be interpreted consistently in case of ambiguity and in case of different options to exchange the same set of information. Such agreements will normally be brought up by an implementer and agreed within the Implementer Support Group. Most likely the ISG group meetings are the place to make final agreements and allow for the feedback from the Model Support Group on the correct interpretation of the IFC specification.

The MSG Coordinator will collect all agreements forwarded to him in this folder. Once entered they are official agreements for the upcoming certification events. As a side effect, they might be used in future to enhance the next IFC releases in order to improve documentation and to reduce ambiguity.

MSG = Model Support Group, the core group of IAI which models the IFC data schema - see www.iai-tech.org for more information on MSG, its coordinator and members and the core buildingSMART deliverables.