Actually the way it was spoken about earlier the +10 was used for this purpose.
They were planning to only stay there for 5 days, but by making a 10 day reservation they get the 180 + 10. If they were to reserve for just the days they actually intended to go it would be 180 +5.
Soooo...if they were planning on going there on the 6th of March they would make reservations starting on the 1st of March. They would then set ADR for that time, including the last 5 days because the chance of getting what they want would be slightly better since fewer people would have access to reserving on those dates. Sometime after they make those ADR's they would cancel the first 5 days of the trip, keeping the last 5 in place thus making it easier to get exactly what they want.
To me it seems like a lot of work and a lot of lying to get something they might have gotten if they had been honest to begin with. In other words, it's an attempt to "work" the system, but to me seems a lot like an unnecessarily complex attempt.
Anytime you make a resort reservation it is automatically 180 + whatever the duration of your stay is. 180 represents the first day you are there. If you stay 1 through 10 days you can put + in front of those days. +1, +2, +3, etc.
I hope that explains it...it's the best I could do!