[SOLVED] What's "ANSI_X3.4-1968" encoding?

What's "ANSI_X3.4-1968" encoding?

See following output on my system:

$ python3 -c 'import sys; print(sys.stdout.encoding)'
ANSI_X3.4-1968

$ locale
LANG=C
LANGUAGE=en_US:en
LC_CTYPE="C"
LC_NUMERIC="C"
LC_TIME="C"
LC_COLLATE="C"
LC_MONETARY="C"
LC_MESSAGES="C"
LC_PAPER="C"
LC_NAME="C"
LC_ADDRESS="C"
LC_TELEPHONE="C"
LC_MEASUREMENT="C"
LC_IDENTIFICATION="C"
LC_ALL=C

Googled but found very little info about it. Even Python's The Python Library Reference (v3.5.2) does not mention it. Any international standard defines it?

(Copied the authoritative ref from the accepted answer's comment: Character Sets)

Solution

This is another name for USAS X3.4-1968, a revision of ASCII that is distinguished by being:

the first revision to allow a linefeed (LF) to occur on its own (i.e. not preceded by or followed by a carriage return (CR)).
the revision that introduced the common name of (US-)ASCII.

This is basically ASCII as we think of it, although there were two minor revisions that followed it.