Language Reference

Names

A name is a sequence of any or all of the following elements:

• Letters (A-Z, a-z)
• Digits (0-9)
• Underscores (_)
• Dollar signs ($)

The first character of a name must not be a digit.

In Fortran 90 and Fortran 95, the maximum length of a name is 31 characters.

+-------------------------------IBM Extension--------------------------------+

In XL Fortran, the maximum length of a name is 250 characters. Although XL Fortran allows a name to start with an underscore, you may want to avoid using one in that position because the AIX^(R) operating system, and the XL Fortran compiler and libraries have reserved names that begin with underscores.

All letters in a source program are translated into lowercase unless they are in a character context. The character contexts are characters within character literal constants, character-string edit descriptors, and Hollerith constants.

Note:

If you specify the -qmixed compiler option, names are not translated to lowercase. For example, XL Fortran treats

ia Ia iA IA

the same by default, but treats them distinctly if you specify the -qmixed compiler option.

+----------------------------End of IBM Extension----------------------------+

A name can identify entities such as:

• A variable
• A constant
• A procedure
• A derived type
• A construct
• A CRITICAL construct
• A program unit
• A common block
• A namelist group

A subobject designator is a name followed by one or more selectors (array element selectors, array section selectors, component selectors, and substring selectors). It identifies the following items in a program unit:

• An array element (see Array Elements)
• An array section (see Array Sections)
• A structure component (see Structure Components)
• A character substring (see Character Substrings)