My wife is a teacher and my 2 daughters were A/B Honor roll students so we have heard about this program.
If I understand it correctly, it's a standardized but advanced curriculum that ensures the proper courses to get into colleges both in this country as well as internationally....hence the name....
A number of the courses in this program are college level and will count as fully credited with colleges who are also part of this program. It lets high school kids get some of the classes the colleges require for a degree program completed in high school.
We opted NOT to have our girls go into this program due to the way it was done here in this county. Only one school in the system had the classes and it was across the country, and the workload was seriously heavy. Lots of homework.... more so than the normal heavy school work load. My wife did most of the research into the pro's and con's of having our girls in this program. For their future plans, it didn't make much sense.
So, they finished their high school days in the normal classes and went on to college regardless...and with scholarships.