Developer Documentation Library > Data Model > Accessing the UNICOM Intelligence Data Model > Working with the Metadata Model
 
Working with the Metadata Model
The Metadata Model (MDM) is implemented as a COM component (mdm2.dll) which is used to instantiate an MDM Document. The MDM Document can be populated in two ways:
From metadata stored in an XML file whose structure reproduces that of the MDM Document. These files usually have the filename extension .mdd and are referred to in this documentation as .mdd files.
Using a metadata source component (MDSC), which exposes metadata stored in a proprietary format, such as Surveycraft or Quanvert.
Consumer applications can access the metadata in the populated MDM Document using the objects, methods, and properties of the MDM.
Although the structure of the XML in an .mdd file reproduces that of the MDM Document, it is not intended to be used as a direct source of metadata. Metadata access should always take place through the MDM Document's interfaces.
The Metadata Model is extensible so that it can support additional information required by specific tools.
See also
MDM Document structure
Working with the Metadata Model: Tutorial
Understanding the MDM features
MDM custom properties
Metadata
Understanding the MDM features
Derived variables
Accessing the UNICOM Intelligence Data Model