law: 89. Summoning witnesses.
  (1) The convening officer, the presiding officer of a Security Force Court, the Law Officer or, as the case may be, the officer approved under section 83 or the Commandant of the accused person may, by summons under his hand, require the attendance, at a time and place to be mentioned in the summons, of any person either to give evidence or to produce any document or other thing.
  (2) In the case of a witness who is subject to this Act, the summons shall be sent to his Commandant and such officer shall serve it upon him accordingly.
  (3) In the case of any other witness; the summons shall be sent to the magistrate within whose jurisdiction he may be, or resides, and such magistrate shall give effect to the summons as if the witness were required in the court of such a magistrate.
  (4) When a witness is required to produce any particular document of other thing in his possession or power, the summons shall describe it with reasonable precision.