|--- SCHC ACK Header --|- W=w1 -|...|-------- W=wi -------|
         |--T-|---M--|-1-|        |...|---M--|
  +------+----+------+---+--------+...+------+--------------+
  |RuleID|DTag| W=w1 |C=0| Bitmap |...| W=wi |0 1 1 1 1 1 1 |
  +------+----+------+---+--------+...+------+--------------+
                         next L2 Word boundary ->|

                 SCHC Compound ACK with Uncompressed Bitmap

  |--- SCHC ACK Header --|- W=w1 -|...|-- W=wi --|
         |--T-|---M--|-1-|        |...|---M--|
  +------+----+------+---+--------+...+------+---+
  |RuleID|DTag| W=w1 |C=0| Bitmap |...| W=wi |0 1|
  +------+----+------+---+--------+...+------+---+
                         next L2 Word boundary ->|

        Transmitted SCHC Compound ACK with Compressed Bitmap