MidiEx

• MDX files may be created by MIDI audio programs as raw memory dump files called MidiEx files, created after an error occurs in order to log what happened.
  
  

LabelPro

• The MDX extension is used by the program LabelPro, a label-maker developed by Avery. LabelPro MDX files are behind-the-scenes index data files.
  
  

Multiple Index File

• MDX could mean a "multiple index file," which refers to a data file containing database information from a database-building program.
  
  

Multiple Index File Programs

• Borland InterBase, developed by Borland Software, and dBASE IV, developed by dataBased Intelligence, both open "multiple index file" files.
  
  

Rational XDE Model File

• MDX could also refer to a model file used by the IBM program Rational XDE, an application development studio.