Index file created by Alpha Five, a Web, desktop, and mobile application IDE; contains an index of the table dictionary, which consists of a .DDD, .DDM, and DDX file; used by Alpha to locate a specific element such as a field rule or form name.

For every table you create in Alpha Five, a DDM, DDD, and DDX file will be created. These files make up the table data dictionary for a DBF file. The dictionary stores saved utility settings, layouts, and queries. It's referenced by Alpha Five to expand the capabilities of the DBF file. DDX files should be kept with the DDD and DDM Data Dictionary files in order for Alpha to find all of the elements and their pieces. NOTE: In 2013, Alpha Five became Alpha Anywhere.