Description
http://en.wikipedia.org/wiki/UTF-16/UCS-2#Encoding_of_characters_outside_the_BMP
From rfc 4627:
To escape an extended character that is not in the Basic Multilingual
Plane, the character is represented as a twelve-character sequence,
encoding the UTF-16 surrogate pair. So, for example, a string
containing only the G clef character (U+1D11E) may be represented as
"\uD834\uDD1E".