# Package org.eclipse.emf.cdo.common.model

Common concepts for dealing with models and types.

- Interface Summary
  Interface | Description
  --- | ---
  CDOClassifierRef.Provider | Provides `classifier references`.
  CDOClassInfo | An EMF `adapter` that encapsulates CDO specific information about an `EClass`.
  CDOModelConstants | Symbolic model constants commonly used in CDO.
  CDOPackageInfo | Describes a single `package` instance of the nested package tree strucure represented by the containing `package unit`.
  CDOPackageRegistry | An EMF `package registry` that is used by CDO `repositories` and `sessions`.
  CDOPackageTypeRegistry.CDOObjectMarker | A common marker interface for CDO (native) objects.
  CDOPackageUnit | Represents a tree structure of nested `packages` that are registered with a `package registry` and that can only be serialized as a whole.
  CDOType | Provides access to all CDO-supported data types.

- Class Summary
  Class | Description
  --- | ---
  CDOClassifierRef | References an `EClassifier`.
  CDOModelUtil | Various static helper methods for dealing with CDO meta models.
  CDOPackageRegistryPopulator | Populates a `target` package registry by asynchronously polling a `source` package registry for new `EPackage` registrations.
  CDOPackageRegistryPopulator.Descriptor | A package `descriptor` that resolves `packages` from a `source` package registry.
  CDOPackageTypeRegistry | A `singleton` registry for the `package unit types` of EMF `packages`.
  EMFPredicates | Predefined `predicates` to test for various `feature` types.
  EMFUtil | Various static helper methods for dealing with EMF meta models.
  EMFUtil.ExtResourceSet | An extension of `ResourceSetImpl` that allows demandLoading of resources and delegation of resource lookups, to be switched on/off as desired.

- Enum Summary
  Enum | Description
  --- | ---
  CDOFeatureType |
  CDOPackageUnit.State | Describes the possible states a `package unit` may be in during its lifecycle.
  CDOPackageUnit.Type | Describes the `instances` of `classes` of a `package unit`.