13.5.25 READWRITE Specifier

The READWRITE specifier asks whether a file can be both read and written to. It takes the following form:

READWRITE = rdwr

rdwr
Is a scalar default character variable that is assigned one of the following values:

'YES'	If the file can be both read and written to
'NO'	If the file cannot be both read and written to
'UNKNOWN'	If the processor cannot determine whether the file can be both read and written to