Enterprise Architect offers support for exporting packages to XMI under the Meta-Object Facility (MOF) 1.3 and 1.4 standards. MOF models are created by assigning the stereotype Metamodel to the package. MOF models can be exported to MOF 1.3 or MOF 1.4 XMI file specification.
MOF is an Object Management Group (OMG) standard that originated in the UML, when the OMG required a Meta-Modeling architecture to define the UML. MOF is designed as a four-layered architecture, as illustrated in the following diagram.
Because of the similarities between the MOF-model and UML structure models, MOF meta-models are usually modeled as UML Class diagrams. You can also use the Metamodel page of the Enterprise Architect UML Toolbox to create MOF model elements and connectors. A supporting standard of MOF is XMI, which defines an XML-based exchange format.
MOF is a closed, strict meta-modeling architecture; every model element on every layer is strictly an instance of a model element of the layer above. MOF only provides a means to define the structure or abstract syntax of a languages or of data.
Simplified, MOF uses the notion of classes, as known from object orientation, to define concepts (model elements) on a meta-layer. These classes (concepts) can then be instantiated through objects (instances) of the model layer below. Because an element on the M2 layer is an object (instance of an M3 model element) as well as a class (an M2 layer concept) the notion of a clabject is used. Clabject is a merge of the words class and object.
Another related standard is OCL, which describes a formal language that can be used to define model constraints by means of predicate logic.