UCS-2 and its relationship to Unicode (UTF-16)
The UCS-2 standard, an early version of Unicode, is limited to 65 535 characters. However, the data processing industry needs over 94 000 characters; the UCS-2 standard has been superseded by the Unicode UTF-16 standard.
The IBM® i operating system supports CCSID 13488, defined as UCS-2, and CCSID 1200, defined as UTF-16. The system treats both CCSID 13488 and CCSID 1200 as UTF-16 encodings.
Using either scheme, you will have the same results for almost all system operations. However, certain SQL functions that operate on a character boundary defined by the SQL standard can produce different results. For instance, the SQL functions of CHARACTER, LENGTH, POSITION, and SUBSTRING distinguish UTF-16 and UCS-2, and therefore you get different results. See the SQL reference for more information about these functions.
UCS, UCS-2 (Universal Multiple-Octet Coded Character Set)
The ISO 10646 standard is a character code designed to encode text for storage in computer files. The design of the ISO 10646 standard is based on today's prevalent character code, ASCII (and ISO 8859-1, an extended version of the ASCII code). But ISO 10646 goes beyond ASCII's ability to encode only the Latin alphabet. The ISO 10646 encoding provides the capability to encode all of the characters used for written languages throughout the world.