Originally Posted by Aggie94

Else Start Next Bid Group (ESN) applies to a single bid line and can be used for a Set Condition, Avoid or Prefer Off. It tells PBS that if it can't honor that particular line to move to the next bid group. You can use ESN on one or more lines in a bid group.

Clear Schedule and Start Next Bid Group (CSSN) does two things:
1) EVERY Set Condition, Avoid and Prefer Off in the bid group must be honored or PBS goes to the next bid group. This means there is no such thing as Denial mode in a bid group with a CSSN. Essentially, PBS treats every Set Condition, Avoid and Prefer Off in the bid group as if it has an ESN on it.
2) PBS can only use the specific Award statements you give it in the bid group. It will not use the system-generated Award Pairings statement in the bid group.

It is very easy to shoot yourself in the foot with the CSSN command.