f is a format identifier and can be:
An asterisk (*), which indicates list-directed I/O. See "List-Directed I/O " on for more information.
The label of a FORMAT statement that appears in the same program unit.
An integer variable name that has been assigned the label of a FORMAT statement that appears in the same program unit.
A character expression or integer array that specifies the format string. The integer array is nonstandard. @