Compaq Fortran 77 is based on American National Standard FORTRAN-77 (ANSI X3.9-1978), and conforms to Federal Information Processing Institute standard FIPS 69-1. (Compaq Fortran 77 is a subset of American National Standard Fortran 90 (ANSI X3.198-1991), which is the same as International Standards Organization standard ISO/IEC 1539:1991.)
Compaq Fortran 77 includes support for programs that conform to the previous standard (ANSI X3.9-1966), and programs that conform to the International Standards Organization standard ISO 1539-1980 (E), because the ISO standard is equivalent to the ANSI standard.
On VAX processors, Compaq Fortran 77 also includes support for
programs that conform to the Multivendor Integration Architecture
(MIA) standard (Technical Requirements TR550001, Nippon Telegraph
and Telephone Corporation, 1991,1992).
Compaq Fortran 77 provides a number of extensions to the ANSI
Standard. Most of these extensions are platform-independent, that
is, they are available on all platforms, but some extensions are
platform-specific.