Open Watcom FORTRAN 77 Language Reference

Input/Output
10.6 Specifiers
All input/output statements contain one or more specifiers. They appear in a list separated by commas.
Some of the more common specifiers are those listed below. Not all of them need be used in every
input/output statement. You should consult the description of the input/output statement under
consideration to discover which specifiers are allowed and what they mean.
[UNIT =] u
[FMT =] f
REC = rn
IOSTAT = ios
ERR = s
END = s
the unit specifier
the format specifier
the record specifier
the input/output status specifier
the error specifier
the end-of-file specifier
We shall look at these specifiers in more detail.
10.6.1 The Unit Specifier
The form of a unit specifier in an input/output statement is:
[UNIT =] u
u is an external unit identifier or an internal file identifier.
1. An external unit identifier is a non-negative integer expression or an asterisk
(*) in which case unit 5 is assumed for an input statement and unit 6 is assumed
for an output statement. The unit identifier must not be an asterisk for the
BACKSPACE, ENDFILE and REWIND statements.
2. An internal file identifier is the name of a character variable, character array,
character array element, or character substring.
If the optional UNIT= specifier is omitted then the unit specifier must be the first item in the list of
specifiers.
10.6.2 Format Specifier
The form of a format specifier in an input/output statement is:
[FMT =] f
f is a format identifier. A format identifier is one of the following:
1. A statement label of a FORMAT statement that appears in the same program unit
as the format identifier.
2. An integer variable name that has been assigned the statement label of a
FORMAT statement that appears in the same program unit as the format identifier
(see the ASSIGN statement).
3. An integer array name.
4. A character array name.
Specifiers 221