According to the article, PHP can handle other encodings by just treating sequences of strings as byte sequences and not caring what the encoding is. There example:

$string = "漢字";

But if you are using say UTF-8 and one of those Chinese characters has one of its bytes have a value of 34 (the ascii value of "), then wouldn't the string terminate prematurely?

Edit: to answer my own question, quote from wikipedia: ASCII bytes do not occur when encoding non-ASCII code points into UTF-8