A Device Description ("DD") is a formal description of the data and operating procedures for a field device, including commands, menus and display formats. It describes exactly what you can do to that particular device by HART communication. It is written as plain text, but is converted into a coded ("tokenised") form for use, for greater efficiency.
See also for details: http://www.hartcomm.org/protocol/about/ddl_use.html
Flow Meter and Flow Controller Solutions by Brooks Instrument
Every day, customers turn to Brooks Instrument for solutions to their flow meter, pressure, and level challenges. In industries as diverse as bio pharmaceuticals, oil and gas, fuel cell, solar, chemicals, medical devices, analytical instrumentation, and semiconductors, Brooks provides the broadest array of flow meter products in the market. Our award- winning flow meters and flow controllers consistently rank at the top of their category for accuracy, reliability, and user preference, as judged by the audience that matters – users of flow meter and flow controller instruments.
HART Device Description files (DD’s) for the SMM transmitter in a MT3809 /
DeviceNet: EDS files for GF100 Series / 
