Please excuse the naive question, but I've never had higher status on UA than 1P, so an SWU is a very rare instrument to me.

Yesterday, the LAX supervisor gave me an SWU to make up for some massive inconvenience (was supposed to fly SNA/ORD/BOS in paid F, received an automated call 3 hours before flight time saying flight was canceled and I'd been rebooked, turned out I was rebooked for 24 hours later, spent an hour on the phone with the ICC, finally booked for same day out of LAX, had to drive an hour and, now, pay for a week's parking at LAX).

I've only had one SWU before and used it to upgrade a coach seat to C on an SFO/HKG flight last year.

I'm going to HKG next week in paid C. Can I use the SWU to upgrade to F? I assume it's on an, "seats available" basis, but must they be upgrade-only seats, i.e. capacity controlled, or do I get the upgrade if there is an unbooked seat in F?

I've got another China trip coming up in September or October, and if I can't use the SWU now, I'll use it then to upgrade a coach ticket. However, I've never flown true international F (no debates, please, about UA's international F product), and I'd like to do it.

I should add that, after a number of years as 1P, this year I have no status due to changing jobs and not flying much last year. An FTer was kind enough to gift me 3P, and, after this trip, I will have earned 2P, and after the HKG trip, I should be back to 1P.

Advice is appreciated.