#\u

[reader syntax] #\uXXXX

SISC, Gauche: denotes a character whose codepoint in Unicode is XXXX, represented in hexadecimal integer.

SISC covers UCS2. Gauche covers more.

Related: Bigloo has separated type for UCS2 character. See ucs2?.

R6RS defines #\xXXXX for unicode character U+XXXX. (The number of digits doesn't need to be 4). See #\x.