Source : Free On-Line Dictionary of Computing

Fortran 90
     
        (Previously "Fortran 8x" and "Fortran Extended") An extensive
        enlargement of {Fortran 77}.  Fortran 90 has {derived type}s,
        {assumed shape array}s, {array section}s, functions returning
        arrays, case statement, {module} subprograms and internal
        subprograms, optional and keyword subprogram arguments,
        {recursion}, and {dynamic allocation}.  It is defined in ISO
        1539:1991, soon to be adopted by {ANSI}.
     
        ["Fortran 90 Explained", M. Metcalf et al, Oxford University
        Press 1990].
     
        (1994-12-16)