core (meta-)model at the heart of EMF. It allows expressing other models by leveraging its constructs. Ecore is also its own metamodel (i.e.: Ecore is defined in terms of itself).

According to Ed Merks, EMF project lead, "Ecore is the defacto reference implementation of OMG's EMOF" (Essential Meta-Object Facility). Still according to Merks, EMOF was actually defined by OMG as a simplified version of the more