There is very little proper Fortran 77 in the world. Legacy Fortran almost always uses extension from MIL-STD-1753 and we should call most legacy Fortran “Fortran 80” to reflect when those compiler features would have been broadly available.
I agree completely – nearly every bit of code I see someone call “FORTRAN 77” isn’t at all. Sure, there are the obvious things such as INTEGER*4 and STRUCTURE/RECORD that are extensions that never made it into any standard. But I’ll often see INCLUDE or END DO, which were also not part of FORTRAN 77; they were part of another standard, MIL-STD-1753.More