I had a system like this in my high school too, but technically it's not "out of 4.0". The maximum possible grade is usually dependent on what courses the student takes. For example, if you took an "honors" course, an A would get you 4.5, B would be 3.5, etc. If you took a "high honors" or "AP" course, A would be 5, B would be 4, etc. If you know what classes you took, you can calculate your maximum score possible.
If he had said he got a 4.4 (or whatever) out of 4.6, it would convey more information than what he said on his resume for two reasons:
1) It would tell the employer at roughly what rate he took harder courses than he had to (this would be especially true if he somehow found the school's average maximum GPA).
2) It would tell the employer the actual ratio of his grades to the maximum possible score.
If I recall correctly (and i graduated high school 10 years ago), so I may be a bit fuzzy on this. But in THEORY you could not calculate a max "out of 4.6" because you could take more credits than the baseline by taking summer school, college courses, etc.
So one could end up with an "average" of 6.3 or 7 since they are divided by the baseline (i think it was like 28 classes? at 4points max each so 112) so assume I took ALL AP classes all 4 years, I'd get a 140/28 (7 classes/year/4 years?)
I think my school's valedictorian had like a 6.X gpa.
Never heard of that sort of system, and I'd never before heard of a valedictorian having a GPA too far north of the 4.6 region. Well...I suppose it's difficult to say if my experience applies generally (I'm sure it doesn't). However, at least in my high school, the absolute maximum possible was something like 4.6. You could, and we regularly did, calculate it based on your own classes. External classes would usually be counted either as honors or AP (unless it was a remedial course).
