- https://en.wikipedia.org/wiki/Unicode_control_characters
- https://unicodebook.readthedocs.io/good_practices.html
- https://en.wikipedia.org/wiki/Plane_(Unicode)
- https://www.soscisurvey.de/tools/view-chars.php
- https://japanese.stackexchange.com/questions/6872/are-the-4-byte-utf-8-kanji-rare-enough-that-i-can-ignore-them