> Windows newlines not withstanding

“Windows” newlines are also the standard in many communication protocols like HTTP and SMTP. That’s not because of Windows or DOS, it’s because it was the standard for teletypes which needed bot CR and LF. It’s arguably systems like Unix that deviated from that standard.

I agree that beyond ASCII there is a slope from well-supported to less-supported and quirky to problematic areas of Unicode. For example, HN filters many Unicode text elements like combining characters (Zalgo text) and emojis, and there is no specification to point at what it supports.

Even within ASCII, most control characters don’t have a portable meaning. So it’s really just the printable subset of ASCII, and strictly speaking not even that, given that there are regional variants of ASCII, such as the Japanese one where backslash becomes the Yen sign.

UNIX (and Linux) is even more annoying because pseudo TTYs will require CRLF when in raw mode but requires only LF when in line mode.