Unit Identifier

This may have any of the following forms:

UNIT= integer-expression The value of the expression must be zero or greater and must refer to a valid I/O unit.

UNIT=* For the standard pre-connected input or output file.

UNIT=internal-file The internal-file may be a variable, array-element, substring, or array of type character, see section 10.3.

Note that the keyword UNIT= is optional if the unit identifier is the first item in the control list.