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, underscores ( _ ), and the dollar sign ($) special character. The first character must be a letter or a dollar sign..

In Fortran 95/90, a name can contain up to 31 characters. Compaq Fortran allows names up to 63 characters.

The length of a module name (in MODULE and USE statements) may be restricted by your file system.

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Note: Be careful when defining names that contain dollar signs.

On OpenVMS systems, naming conventions reserve names containing dollar signs to those created by Compaq. On Tru64 UNIX, Linux, and Windows systems, a dollar sign can be a symbol for command or symbol substitution in various shell and utility commands.

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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:

Examples

For details on the scope of names, see Section 16.1.