text: FM 2-22.3
  Appendix F
  NATO System of Allocating Interrogation Serial Numbers
  1. Every captured person selected for interrogation will be given an Interrogation Serial
  Number. This number shall be allocated by the Interrogation Unit conducting the first
  interrogation of the captured person.
  2. The number should not be confused with the Prisoner of War Internment Serial Number
  (ISN), which is to be used for administrative purposes only.
  3. The purpose of the Interrogation Serial Number is to identify the source of information to
  ensure its proper evaluation, processing, and follow-up action. It will also identify the nationality
  and location of the interrogation unit.
  4. The number shall be constituted as follows:
  a. 2 letters to indicate the Nationality of the captured person (see para 6).
  b. 2 letters to indicate the Service of the captured person (see para 7).
  c. 1 letter to indicate the Arm of Service of the captured person (see para 8).
  d. 4 numbers to indicate the Interrogation Sequence Number of the captured person (see
  para 9).
  e. 4 numbers to indicate the Day and Month of Capture.
  f. A dash (-) to show a sequence break.
  g. 4 letters to indicate the Nationality and Service of the Interrogation Unit (see para 10).
  h. 4 letters to indicate the Interrogation Unit.
  5. Each group shall be separated by a dash. The final number shall therefore appear as in the
  following examples:
  LS – NV – B – 0012 – 2105 – USNV – 0159
  Liechtenstein – Naval prisoner – Seaman – 12th captured person interrogated -
  captured 21 May – interrogated by US Navy – team 159
  AN – AF – H – 0357 – 0211 – GEAF – 0007
  Andorra – Air force prisoner – Intelligence – 357th captured person interrogated –
  captured 2 Nov – interrogated by GE Air Force – team 7