A single-byte character is one whose numeric value is expressible in one byte
A double-byte character is one whose numeric value is expressible in two bytes
A triple-byte character is one whose numeric value is expressible in three bytes
An n-byte character is one whose numeric value is expressible in exactly n bytes
A multi-byte character is one whose numeric value is not expressible in a single byte
Note: A double-byte code page can contain single-byte characters and double-byte characters. A triple-byte code page can contain single-byte characters, double-byte characters, and triple-byte characters, and so on.