2.1.2 Names

Names identify entities within a Fortran program unit (such as variables, function results, common blocks, named constants, procedures, program units, namelist groups, and dummy arguments). In FORTRAN 77, names were called "symbolic names".

A name can contain letters, digits, an underscore ( _ ), and the dollar sign ($) special character. A name can contain up to 31 characters; the first character must be a letter.

Note

Be careful when defining names that contain dollar signs. On OpenVMS systems, naming conventions reserve names containing dollar signs to those created by DIGITAL. On DIGITAL UNIX, Windows NT, and Windows 95 systems, a dollar sign can be a symbol for command or symbol substitution in various shell and utility commands.

In an executable program, the names of the following entities are global and must be unique in the entire program:

• Program units

• External procedures

• Common blocks

• Modules

Examples

The following examples demonstrate valid and invalid names:

Valid
NUMBER
FIND_IT
X
Invalid	Explanation
5Q	Begins with a numeral.
B.4	Contains a special character other than _ or $.
_WRONG	Begins with an underscore.

For More Information:

For details on the scope of names, see Section 15.1.