All electronic systems developed for the US forces are given a designation
under the Joint Electronics Type Designation System (JETDS), sometimes
called the "AN" system.

All designations start with "AN/" (I don't know what the "AN" stands for;
something like "article number"?) This is followed by three letters
describing the item, a dash, and a number.  The number is sometimes
followed by a "variable group", consisting of "(V)" to indicate a variant,
optionally followed by another number to indicate subsequent variants.

For example, the radar in the F-16C/D is designated AN/APG-68.  The "APG"
part can be broken down into an installation code of "A" (piloted
aircraft), an equipment type code of "P" (radar), and a purpose code of "G"
(fire control).  If variants were developed, they would be designated
"AN/APG-68(V)", "AN/APG-68(V)2", and so on.

First letter -- Installation:
    A -- Piloted aircraft
    B -- Submarine
    C -- Air transportable
    D -- Pilotless carrier
    E -- Blank
    F -- Fixed ground installation
    G -- General purpose
    K -- Amphibious
    M -- Ground mobile
    P -- Portable
    S -- Water
    T -- Ground transportable
    U -- General utility assemblies
    V -- Ground vehicle
    W -- Water surface/underwater combination
    Z -- Piloted/pilotless airborne combination

Second letter -- Equipment type:
    A -- Infrared/ultraviolet
    C -- Carrier
    D -- Radiac
    E -- Nupac
    F -- Photographic
    G -- Telegraph/teletype
    I -- Interphone/public address
    J -- Electromechanical/inertial wire covered
    K -- Telemetering
    L -- Countermeasure
    M -- Meteorological
    N -- Sound in air
    P -- Radar
    Q -- Sonar/underwater sound
    R -- Radio
    S -- Special types
    T -- Telephone (wire)
    V -- Visible light
    W -- Armament
    X -- Facsimile/TV
    Y -- Data processing

Third letter -- Purpose:
    A -- Auxiliary
    B -- Bombing
    C -- Communications
    D -- Direction finding/reconnaissance/surveillance
    E -- Ejection/release
    G -- Fire control/light finding
    H -- Recording/reproducing
    K -- Computing
    M -- Maintenance/test
    N -- Navigational aids
    Q -- Special purpose/combination
    R -- Receiving/passive detecting
    S -- Detection/range bearing/search
    T -- Transmitting
    W -- Automatic flight/remote control
    X -- Identification/recognition
    Y -- Surveillance/control