Fortran Wiki
Keywords

Keywords are specifically NOT reserved words as per the Fortran specifications (F03 section 2.52, F90 section 2.52, and F77 section 2.2).

FORTRAN 77

The following keywords were defined in FORTRAN 77: assign, backspace, block data, call, close, common, continue, data, dimension, do, else, else if, end, endfile, endif, entry, equivalence, external, format, function, goto, if, implicit, inquire, intrinsic, open, parameter, pause, print, program, read, return, rewind, rewrite, save, stop, subroutine, then, write.

Fortran 90

The following keywords were added in Fortran 90: allocatable, allocate, case, contains, cycle, deallocate, elsewhere, exit?, include, interface, intent, module, namelist, nullify, only, operator, optional, pointer, private, procedure, public, recursive, result, select, sequence, target, use, while, where.

Fortran 95

The following keywords were added in Fortran 95: elemental, forall, pure.

Fortran 2003

The following features were added in Fortran 2003: abstract, associate, asynchronous, bind, class, deferred, enum, enumerator, extends, final, flush, generic, import (in interfaces), non_overridable, nopass, pass, protected, value, volatile, wait.

Fortran 2008

The following keywords were added in Fortran 2008: block, codimension, do concurrent, contiguous, critical, error stop, submodule, sync all, sync images, sync memory, lock, unlock, impure.

Fortran 2018

The following keywords were added in Fortran 2018: select rank, non_recursive, import (in block and contained procedures).