FD Entry: CODE-SET clause
The FD Entry for an ASCII-encoded file must contain a CODE-SET clause; the alphabet-name must be associated with STANDARD-1 (for the ASCII code set) in the SPECIAL-NAMES paragraph.
For example:
Special-names. Alphabet ASCII-sequence is standard-1.
...
FD ASCII-file label records standard
Recording mode is f
Code-set is ASCII-sequence.