AN-

Most U.S. military electronics equipment has designations in the form AN/ABC-99. This always-evolving system began as the Joint Electronics Type Designation System. Information security equipment under the control of the National Security Agency belongs to the TSEC/XYZ series, except certain of the letters in the AN/ system are reserved for NSA use.

While the designation systems are quite complex and still contain special cases, the basic structure is:
 * First letter: Where or how is it installed?
 * Second letter: What kind of information or energy does it handle/
 * Third letter: What does it do with the information or energy?

The next numbers indicate a main model number within the series, followed by a bewildering and inconsistent set of version levels, alternate configurations, etc. Sometimes, what may seem an incremental improvement gets an entirely new model number, while a radical change may get a version change only. In other words, grasp the general principles of the system, but know that you will have to examine a specific system to understand its designation nuances.

In the table below, only current codes are used; alas, animal-carried systems are no longer designated. Alas, the air-transportable pigeon loft & message center is no longer in service.