A model is a non-redundant description of an object. For example, a 3D plant model is a non-redundant 3D description of a plant (non-redundant = non-excessive).
A model definition (ModelDef) is the schema information used to describe the model.
The primary function of a model definition is to identify those objects that can be shared through a ModelClass relationship. Objects can only be shared if they exist within the same model definition. Objects in different model definitions can be related, but they cannot be shared.
Model definitions define domains of data. The schema contains seven model definitions:
-
MetaModel - Used only by the class definitions in the meta schema. You should never use this model for schema.
-
OrganizationModel - Used for class definitions that are organizational concepts. Examples would be User, Company, Department, Manufacturer, Vendor, and so on.
-
WorkBreakdownModel - Used for class definitions that provide organizations of work. This includes the class definitions that you see in the WBS documents such as Project and Contract as well as all the document class definitions defined in the schema.
-
FacilityModel - Used for class definitions that represent abstract concepts in a process plant. Examples include Plant, Area, Unit, System, Discipline (although you could put Discipline in the OrganizationModel instead.)
-
PlannedMaterialModel - Used for class definitions that represent real objects that you plan to purchase to construct your design. This is the "design" arena in which engineering tools like Aspen Basic Engineering, Smart P&ID, and Smart Instrumentation work.
-
TypicalMaterialModel - Used for class definitions that represent real objects offered by manufacturers or vendors. When an engineer looks for an object to fulfill the requirements of his design, he might look through a manufacturer catalog. This is the domain of this model.
-
ActualMaterial - Used for class definitions that represent what is purchased and assembled to construct the plant.
Evolution for objects is normally from planned facility (FacilityModel) to planned material (PlannedMaterialModel) to actual material (ActualMaterialModel). Catalog parts are part of the typical material model. Meta schema objects are part of the meta model. The organization model contains objects that are outside the normal set of designed objects; these objects describe the organization rather than the design. The work breakdown model contains object associated with the work being performed rather than the objects for that work.
All model definitions are predefined in the meta schema and cannot be modified.