I agree, it should only be adding 6 hours for CST... and I guess we're not in daylight savings at the moment (I should've known that). It's adding 7 hours. Don't ask me why. I downloaded the code, added it to my project, and re-built it. I'm doing this:

? DATETIME()
DO UTC_TIME with DATETIME()

I haven't modified UTC_TIME.PRG or any of the other files. I also tried it with the 'Automatically Adjust for Daylight Savings Time' checkbox in Control Panel both on and off. My time zone is set to Central Time, -06:00 hours GMT. It adds 7 hours every time.

The only thing I can think of is I read somewhere that GMT is not always the same as UTC (and sometimes GMT != the current time in Greenwich, as I understand it).

I just switched my time zone to Eastern Time, and it added 6 hours. I'm willing to bet you think it's my computer, and I'm inclined to agree. But what could be wrong that would throw it off that one hour? I would think if anything, it would be one hour less instead of one hour more for daylight savings... This makes no sense at all.