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

 |--- SCHC ACK Header --|-W=w1-|...|-------- W=wi -------|
        |--T-|---M--|-1-|      |...|---M--|              |---M--|
 +------+----+------+---+------+...+------+--------------+------+~~~+
 |RuleID|DTag| W=w1 |C=0|Bitmap|...| W=wi |1 0 1 0 1 1 1 |00..00|pad|
 +------+----+------+---+------+...+------+--------------+------+~~~+
                    next L2 Word boundary ->|<------ L2 Word ------>|
 
                  Transmitted SCHC Compound ACK