That wording is ancient - well, back to 1964 at least, the original FAR25 issue text.. The CAR4b text on the FAA website does NOT include equivalent wording, so it seems to originate about the time the FARs were first introduced.
certainly rules out the An74 though. I wonder if it's some kind of boundary layer blowing idea (such as Buccaneer or A-6) since that was in vogue briefly...