[fanf2]

ASCII 1963 was the first version of the standard and it had ← https://dl.acm.org/doi/10.1145/366707.367524

The 1965 draft had _ instead https://dl.acm.org/doi/10.1145/363831.363839

The first standard edition with _ was 1968 https://www.rfc-editor.org/info/rfc20

The 1977 version is also available https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub1-2-197...

Xerox PARC used ASCII 1963 (for reasons I have yet to unearth) so its programming languages Mesa and SmallTalk used ← for assignment and camelCase to separate words in identifiers. This stylistic quirk was carried over to later object-oriented programming languages.