The implementation or concrete representation of an information model. A data model says what information is to be contained in a datastore, how the information will be used, and how the items in the datastore will be related to each other.
RFC3444 states: "Compared to IMs, DMs define managed objects at a lower level of abstraction. They include implementation- and protocol-specific details, e.g. rules that explain how to map managed objects onto lower-level protocol constructs".
An abstract representation of the entities being managed. An information model definition includes object classes, properties/attributes, methods, and relationships. Often, an information model captures generic concepts, which are applicable across like managed entities.
An abstraction of a managed entity (For example, a managed resource). The managed object definition includes a set of supported attributes, operations, and notifications
A collection of related managed objects forming a logical and consistent grouping.
Object Model Fragment
A uniquely identifiable portion of an object model. It is the equivalent of a single SNMP MIB module, which can be implemented by multiple NEs. It is labeled as a common object model fragment not according to its specification, but because multiple NEs implement it. That is, a subset of all object model fragments are those which are designated as being common because, and only because, they are implemented by more than one NE (that is, an object model fragment does not become common because of any change in its specification.)
XML Schema Definition A way to describe and validate data in an XML environment. A schema is a model for describing the structure of information.