Dimension format files were created by the SPSS Data Collection products in the first decade of the 2000s. They are also often referred to as Dimensions files.
The format consists of an XML file with the extension .mdd. This file contains the metadata. This file can contain a reference to a database that needs to be connected to. Or, it may be accompanied by a file in some other format, such as:
The format is now marketed as Unicom Intelligence.