Biggest difference between Global reserve and Non-Global is that roughly half of your days off are Regulare Days off and in a limited set of circumstances those can be moved by the company without your consent. If the company is trying to cover a Global trip ( Pacific past Hawaii, Europe, and SA south of 15 degrees South) and after following a new more complicated process, the only way to cover the trip is by moving your day(s) off, they can do so.

So, you have 2 days left on reserve followed by 2 days off (Regular Days Off) and a 4 day NRT trip comes open. If they don't have any reserves with 4 or more days available, they will then look at the 3 day guys and then the 2 day guys and then the one day guys, to cover the trip. So, in the case I mentioned if there aren't any reserves with more then 2 days available, you could get your days off moved and be assigned the 4 day trip.

6 of your days off each month are HDOs (Holy Days Off) and those cannot be moved without your consent, so the above moving of days to assign you the 4 day intl would not apply if the days off were HDOs.

The new contract has changed the assignment process on these trips and they have to be offered to line holders at time and a half (at least) before assigning a reserve, and if your day off is moved you now get extra compensation. So, if a reserve is willing to move the day off to get the compensation, they would be able to volunteer for the disruption and they would get used before a reserve getting their day(s) off moved involuntarily. This is supposed to make it less likely that a reserve will get their days moved involuntarily, but at the end of the day they can do it if they need to to get the trip covered.

While this happens fairly rarely, the likelihood of it happening is directly related to the importance of whatever you had planned on those days off!!