Modularity
Fortran

The Fortran module corresponds to the class introduced by Simula 67, to the Ada package, and to the unit of the same name in Extended Pascal and Modula-2. The concept is presented in the article Programming languages. Introduction of this treaty. Its adoption enabled Fortran 90 to make a fundamental qualitative leap forward, and effectively rendered obsolete a number of the most hotly debated previous features (such as COMMON).

The module is a non-executable program unit that reliably exports a set of software resources. Compilable separately, it will form the basis of future Fortran 90 component libraries, eventually replacing (and integrating) the external procedures that were previously the only ones available.