Statements

This chapter describes the various types of Fortran statements.

Fortran statements can be grouped into five categories. They are

Statement Order

There are restrictions on where a given statement can appear in a program unit or subprogram. In general,

USE statements come before specification statements;
specification statements appear before executable statements, but FORMAT, DATA, and ENTRY statements can appear among the executable statements; and
module procedures and internal procedures appear following a CONTAINS statement.

The following table summarizes statement order rules. Vertical lines separate statements that can be interspersed. Horizontal lines separate statements that cannot be interspersed.

Statement Order
PROGRAM, FUNCTION, SUBROUTINE, MODULE, or BLOCK DATA statement
USE statements
FORMAT and ENTRY statements	IMPLICIT NONE
	PARAMETER statements	IMPLICIT statements
	PARAMETER and DATA statements	Derived-type definitions, interface blocks, type declaration statements, statement function statements, and specification statements
	DATA statements	Executable statements
CONTAINS statement
Internal subprograms or module subprograms
END statement

Statements are restricted in what scoping unit they may appear, as follows:

An ENTRY statement may only appear in an external subprogram or module subprogram.
A USE statement may not appear in a BLOCK DATA program unit.
A FORMAT statement may not appear in a module scoping unit, BLOCK DATA program unit, or interface body.
A DATA statement may not appear in an interface body.
A derived-type definition may not appear in a BLOCK DATA program unit.
An interface block may not appear in a BLOCK DATA program unit.
A statement function may not appear in a module scoping unit, BLOCK DATA program unit, or interface body.
An executable statement may not appear in a module scoping unit, a BLOCK DATA program unit, or an interface body.
A CONTAINS statement may not appear in a BLOCK DATA program unit, an internal subprogram, or an interface body.