>It was designed and specified at a time when the Unicode code space had a 21 bit limit 21 bits is the current Unicode limit. Unfortunately UTF-8 in 3 Bytes on

>It was designed and specified at a time when the Unicode code space had a 21 bit limit 21 bits is the current Unicode limit. Unfortunately UTF-8 in 3 Bytes only has 16 usable bits - the first byte starts with 1110 and the two continuation bytes start with 10, so it's 4 + 6 + 6 = 16 bits.