Dom Lopez teaches an approach to attack that he calls "slipping in." A number of specific techniques are classified under this concept. The essential element is that when a blow is intercepted, you can continue your attack with the same arm (or weapon), without first withdrawing. It is similar to what some other teachers call "flow." So for instance, if your straight punch to the head is blocked, you slide off the block and hit to a low target. There are numerous ways of slipping in, and it is worthwhile to add these to your bag of tricks.