AppendRune appends the UTF-16 encoding of the Unicode code point r to the end of p and returns the extended buffer. If the rune is not a valid Unicode code point, it appends the encoding of U+FFFD.

Decode returns the Unicode code point sequence represented by the UTF-16 encoding s.

DecodeRune returns the UTF-16 decoding of a surrogate pair. If the pair is not a valid UTF-16 surrogate pair, DecodeRune returns the Unicode replacement code point U+FFFD.

Encode returns the UTF-16 encoding of the Unicode code point sequence s.

EncodeRune returns the UTF-16 surrogate pair r1, r2 for the given rune. If the rune is not a valid Unicode code point or does not need encoding, EncodeRune returns U+FFFD, U+FFFD.

IsSurrogate reports whether the specified Unicode code point can appear in a surrogate pair.

RuneLen returns the number of 16-bit words in the UTF-16 encoding of the rune. It returns -1 if the rune is not a valid value to encode in UTF-16.