It could be he's thinking of the historical definition which included support for 5 character encoding with a maximum codepoint of U+7FFFFFFF or ~2 billion. ht

It could be he's thinking of the historical definition which included support for 5 character encoding with a maximum codepoint of U+7FFFFFFF or ~2 billion. https://en.wikipedia.org/wiki/UTF-8#History https://en.wikipedia.org/wiki/UTF-8#History That was restricted I believe primarily for compatibility with more limited encodings like UTF-16. I guess it's possible that at some future point in human history when UTF-16 has been purged from memory, the 5 character encoding might be allowed again. :)