text: Appendix B
  the commander wants to deliver the attack. Attack by fire positions are rarely applicable to units larger than
  company size. Figure B-1 on page B-1 depicts the attack by fire tactical mission task.
  B-4. An attack by fire closely resembles the task of support by fire. The chief difference is that one unit
  conducts the support by fire task to support another unit, so the second unit can maneuver against enemy
  forces. The attack by fire task includes—
  * Assigning sectors of fire or engagement areas to each subordinate weapon system to include the
  enemy force’s defensive positions or avenues of approach.
  * Designating control measures for massing, distributing, and shifting of direct and indirect fires.
  * Designating BPs, an assigned area, or an axis of advance to allow the friendly force to engage the
  enemy force.
  * Providing for security and all-around defense, including control measures to ensure tie in of
  subordinate elements and maximum use of hide positions.
  * Using OPSEC to deceive enemy forces about movement, occupation, and intent of the operation.
  * Reconnoitering, preparing, and securing movement routes and firing positions before the
  movement of the main body, and stocking class V items.
  * Providing movement instructions to the initial battle positions.
  BLOCK
  B-5. Block is a tactical mission task that denies the enemy access to
  an area or an avenue of approach. A blocking task normally requires
  the friendly force to block the enemy force for a certain time, or until a
  specific event has occurred. The line perpendicular to the enemy’s line
  of advance indicates the limit of enemy advance. A blocking unit may
  have to hold terrain and become decisively engaged. Block as a tactical
  mission task differs from the tactical mission task of fix. A blocked
  enemy force can move in any direction other than the obstructed one,
  while a fixed enemy force cannot move in any direction. Figure B-2
  depicts the block tactical mission task.
  Figure B-2. Block task
  B-6. Block is also an obstacle effect that integrates fire
  planning and obstacle effort to stop an attacker along a
  specific avenue of approach or prevent the attacking force
  from passing through an engagement area. The vertical line
  in the obstacle effect graphic indicates the limit of enemy
  advance. It also indicates where the obstacle ties in to restricted
  terrain. A force may employ blocking obstacles to assist in the
  task. Blocking obstacles are complex, employed in depth, and
  integrated with fires to prevent enemy forces from proceeding
  along an avenue of approach or to proceed only at unacceptable
  Figure B-3. Block obstacle effect
  cost. When employed, blocking obstacles serve as a limit, not
  allowing enemy forces beyond that point. Obstacles alone cannot accomplish a blocking task. Figure B-3
  depicts the block obstacle effect. (See Chapter 17 for more information on the block obstacle effect.)
  BREACH
  B-7. Breach is a tactical mission task in which a unit breaks through or establishes a passage through
  an enemy obstacle. An enemy obstacle can include enemy defenses, obstacles, minefields, or fortifications.
  Units attempt to bypass and avoid obstacles and enemy defensive positions to the maximum extent possible
  to maintain tempo and momentum. Breaching enemy defenses and obstacle systems is normally the last
  choice. If a breach is necessary, units employ all available means to break through or establish a passage. A
  breach is a synchronized combined arms operation under the control of the maneuver commander.