A representation for a single abstract character that consists of a sequence of two 16-bit code units, where the first value of the pair is a high-surrogate code unit and the second value is a low-surrogate code unit.

• Surrogate pairs are used only in UTF-16.
• Isolated surrogate code units have no interpretation on their own. Certain other isolated code units in other encoding forms also have no interpretation on their own. For example, the isolated byte 8016 has no interpretation in UTF- 8; it can be used only as part of a multibyte sequence.
• Sometimes high-surrogate code units are referred to as leading surrogates. Lowsurrogate code units are then referred to as trailing surrogates. This is analogous to usage in UTF-8, which has leading bytes and trailing bytes.