The set of rules by which graphic characters and control characters are given a specific encoded value. Standards organizations define encoding schemes, such as ASCII, Unicode, and ISO/IEC 10646. For example, in IBM, the EBCDIC encoding scheme is used for AS/400 systems and the PC encoding scheme for PCs. The underlying part of a code page where the following are defined: The coding space (number and allowable value of code points in a code page). The rules for sharing the coding space between control and graphic characters. The rules related to specific options, such as the number of bits in a byte, single-byte, or double-byte, permitted in that scheme. In DB2 UDB for AS/400, a set of rules to represent character data when converting from one type of character data to another, such as from ASCII to EBCDIC.