text: Fire Support Coordination Measures
  B-37. A maneuver BN or higher echelon normally establishes a RFA. Usually, the RFA is located on
  identifiable terrain, by grid, or by a radius from a center point. To facilitate rapidly changing operations, on-
  call RFAs may be used. The dimensions, locations, and restrictions of the on-call RFAs are prearranged.
  B-38. A RFA is graphically portrayed with solid black line defining the area and the letters "RFA" within,
  followed by the establishing HQ and the effective date-time group provides graphic portrayal of the RFA.
  (See figure B-8). The restrictions may be included within the graphic if space allows, or reference may be
  made to a specific OPORD or OPLAN (FM 1-02.2). For example, a commander may identify a particular
  type of ammunition to preclude its firing within the RFA.
  Figure B-8. Restrictive fire area example
  RESTRICTIVE FIRE LINE
  B-39. A restrictive fire line is a specific boundary established between converging, friendly surface forces
  that prohibits fires or their effects from crossing. (JP 3-09). The purpose of the RFL is to prevent fratricide
  and duplication of engagements by converging friendly forces.
  B-40. A RFL (see figure B-9 on page B-14) is graphically portrayed by a solid black line, with "RFL"
  followed by the establishing HQ above the line and the effective date-time group below the line. The
  commander common to the converging forces establishes the RFL. It is located on identifiable terrain when
  possible. In link-up operations, it is usually closer to the stationary force to allow maximum freedom of action
  for the maneuver and FS of the linkup force.