(Previously "Fortran 8x" and "Fortran Extended") An extensive

enlargement of Fortran 77. Fortran 90 has derived types,

assumed shape arrays, array sections, 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.