What about the DRBC-32E, aka Castor 2 for example ?
- The 1st letter stands for the function of the equipment :
- A : electronic warfare, countermeasures
- D : detection
- E : transmitter
- N : IFF or recognition
- R : receiver
- T : transmitter-receiver combination
- The 2nd letter is the general type of equipment :
- F : wireline
- R : radio-electrical
- S : passive detection
- U : ultrasounds, sonar
- The 3rd letter stands for the platform carrying the equipment :
- A : aircraft, plane or helicopter
- B : surface ship
- M : ground mobile
- P : man-portable
- U : submarine
- The 4th letter is the operating mode of the equipment :
- A : active
- B : noise jamming
- C : fire-control
- D : deceptive jamming
- G : direction finding
- I / J : multipurpose
- L : decoy
- N : navigation
- R : interception
- V : surveillance
- The number is the model, and a subsequent letter is a version. For the radar, though, the number denotes the frequency band :
- 10 to 19 : E/F band (10 cm wavelength, 2-4 GHz frequency)
- 20 to 29 : A band (2 m, 0-0.25 GHz)
- 30 to 39 : I band (3 cm, 8-10 GHz)
- 50 to 59 : G band (5 cm, 4-6 GHz)
- As for sonar, a number above 10 denotes equipment with preformed beams.
So, our proposed example, the DRBC-32E is :
- D : a detector
- R : radio-electrical, aka a radar
- B : ship-borne
- C : fire-control
- 32 : 3rd model in I band
- E : in its 5th version

Inspired by the Harpoon 4.1 Rulebook, sidebar 4-13.
Source : Moulin, J., & Maurand, P. (2008). Les frégates anti-sous-marines. Rennes: Marines éd.