The piece documents that at least two manufacturers (Data General and Univac) marketed their extended Fortran IV compilers as "Fortran V" -- but it doesn't say whether they actually extended Fortran IV the same way. "Fortran V" wasn't the name of any official standard; the ANSI standard which more or less documented Fortran IV was officially Fortran 66, and ANSI's next version was Fortran 77.