[Legendary League]

In the few MP games I've done before, all NAPs were conducted in the fashion that we have given you (attack orders sent on turn 15+x, provided you also sent the notice of cancellation on turn 15). So an NAP-0 (an NAP with no cancellation period) would thus have no warning from time of cancellation to time of attack, whilst an NAP-1 would give the defender 1 turn of warning, so on and so forth.

Think of it this way. A cancellation period is how much time and warning a player gets that they're going to be attacked. With no cancellation period, the attack is effectively unannounced. With a 1 turn/month period, the person gets 1 turns worth of warning.