# 4 Specification Statements

A specification statement is a nonexecutable statement that allocates and initializes variables, arrays, records, and structures; and defines other characteristics of symbolic names used in a program.

The following are specification statements:

- AUTOMATIC and STATIC

  Controls the allocation of storage to variables and the initial value of variables within called subprograms.

- BLOCK DATA

  Initiates a series of statements that establish common blocks and assign initial values to entities in named common blocks.

- COMMON

  Defines one or more contiguous areas of storage shared among separate subprograms.

- DATA

  Assigns initial values to variables, arrays, and array elements before program execution.

- Type declaration statement

  Explicitly defines the data type of specified symbolic names.

- DIMENSION

  Defines the number of dimensions in an array and the number of elements in each dimension.

- EQUIVALENCE

  Associates two or more entities with the same storage location.

- EXTERNAL

  Allows use of user-supplied procedures as arguments to subprograms.

- IMPLICIT

  Overrides the implied data type of symbolic names.

- INTRINSIC

  Allows use of Fortran intrinsic procedures as arguments to subprograms.

- NAMELIST

  Specifies lists of entities whose values can be read or written in namelist I/O statements; associates the list with specified group-names.

- PARAMETER

  Associates a symbolic name with a constant value.

- POINTER

  Establishes pairs of variables and pointers, where each pointer contains the address of its paired variable.

- PROGRAM

  Assigns a symbolic name to a main program unit.

- RECORD

  Establishes a record with the structure defined by the block of statements in a structure declaration.

- SAVE

  Retains values of local variables after a return from a subprogram.

- Structure declaration

  Specifies the form of a record.

- VOLATILE

  Prevents optimizations from being performed on specified variables, arrays, and common blocks.

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