text: Tactical Control Measures
  Restrictive Fire Line
  A-99. 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). Both or
  only one of those converging forces may be
  moving. Fires and their effects can cross a RFL
  when the event has been coordinated with the
  affected force. The purpose of the line is to
  prevent interference between converging
  friendly forces, such as what occurs during a
  linkup operation. The next higher common
  commander of the converging forces
  establishes the RFL. Located on identifiable
  terrain, it is usually located closer to the
  Figure A-50. Restrictive fire line
  stationary force—if there is one—than to the
  moving force. Alternatively, a commander can use an RFL to protect sensitive areas, such as cultural
  monuments. Figure A-50 depicts a restricted fire line.
  FIRE SUPPORT TARGETS
  A-100. A target is an entity or object
  that performs a function for the threat
  considered for possible engagement
  or other action (JP 3-60). There are
  control measures for point targets,
  circular targets, rectangular targets,
  and linear targets. Commanders
  designate fire support targets using a
  two-letter and four-digit code
  established in field artillery doctrine.
  A-101. Commanders may choose to
  attack two or more targets
  simultaneously or sequentially. A
  group of targets consists of
  simultaneously engaging two or more
  targets. Commanders graphically
  show a group of targets by circling the
  targets and identifying the group with
  Figure A-51. Fire support targets
  a group designator. This group
  designator consists of the two letters
  assigned to the block of target numbers assigned to a unit with a number inserted between the two letters. A
  series of targets consists of engaging two or more targets sequentially. A series can include individual targets
  or combinations of individual and group targets. Commanders show a series of targets as individual targets
  or groups of targets within a prescribed area. Commanders assign each series a code name or nickname. The
  designation of a series or group of targets does not preclude the attack of individual targets within the series
  or group. It also does not preclude the attack of one or more groups of targets within the series. Figure A-51
  depicts the different fire support targets.
  COMMON AIRSPACE COORDINATING MEASURES
  A-102. Airspace coordinating measures are measures employed to facilitate the efficient use of airspace to
  accomplish missions and simultaneously provide safeguards for friendly forces (JP 3-52). Airspace
  coordinating measures (ACMs) are employed to facilitate the efficient use of airspace to accomplish missions
  and simultaneously provide safeguards for friendly forces. ACMs provide the three-dimensional description