(1) A 2-byte (16-bit) encoding scheme based on ISO/IEC specification 10646-1. UCS-2 defines three levels of implementation: Level 1-No combining of encoded elements allowed; Level 2-Combining of encoded elements is allowed only for Thai, Indic, Hebrew, and Arabic; Level 3-Any combination of encoded elements are allowed.
(2) Universal Character Set, coded in 2 octets, which means that each character is represented by 16 bits. UCS-2 is a subset of UTF-16. See also UTF-8, UTF-16.