4.3.8 Software Identity
An object needs to be identifiable for accurate processing by both human and automated processes. Identification may be through several attributes such as Identification, Name, Description or GUID. The GUID is compressed for the purpose of being exchanged within an IFC data set - the compressed GUID is referred to as "IFC-GUID". While the IFC-GUID is normally generated automatically and has to be persistent, the Identification may relate to other informal registers but should be unique within the set of objects of the same type. The Name and Description should allow any object to be identified in the context of the project or facility being modelled.
Various objects may have additional identifications that may be human-readable and/or may be structured through classification association. Various file formats may use additional identifications of instances for serialization purposes, however there is no requirement or guarantee for such identifications to remain the same between revisions or across applications. For example, the IFC-SPF file format lists each instance with a 64-bit integer that is unique within the particular file.
The following diagram shows the generic classes and relationships used when applying this concept. In addition, concepts may have particular importance to common or standardised industry practices and scenarios. For these specific usage scenarios, the tables below shows a recommended list of general usage patterns that users may adopt.