Northeastern’s weighting system gives +0.5 for honors classes and +1.0 for AP classes.
I’m not sure how they deal with different systems that use pre-IB, IB, and dual enrollment, for example. This also ends up somewhat skewed since the raw weighted GP would end up punishing people for taking additional electives like art or orchestra. It’s some measure for them to compare, but it’s not the end-all measure. I had a 4.0 unweighted with a full IB diploma course and still came out with only a 4.2 weighted GPA by Northeastern’s system because I also took a lot of electives like band and art classes.