In character encoding terminology, a code point or code position is any of the numerical values that make up the code space. Glossary of Unicode Terms Many code points represent single characters but they can also have other meanings, such as for formatting.
For example, the character encoding scheme ASCII comprises 128 code points in the range 0Hexadecimal to 7Fhex, Extended ASCII comprises 256 code points in the range 0hex to FFhex, and Unicode comprises code points in the range 0hex to 10FFFFhex. The Unicode code space is divided into seventeen planes (the basic multilingual plane, and 16 supplementary planes), each with (= 216) code points. Thus the total size of the Unicode code space is 17 × = .
This is because one may wish to make these distinctions to:
For Unicode, the particular sequence of bits is called a code unit – for the UCS-4 encoding, any code point is encoded as 4-byte (octet) , while in the UTF-8 encoding, different code points are encoded as sequences from one to four bytes long, forming a self-synchronizing code. See comparison of Unicode encodings for details. Code points are normally assigned to abstract characters. An abstract character is not a graphical glyph but a unit of textual data. However, code points may also be left reserved for future assignment (most of the Unicode code space is unassigned), or given other designated functions.
The distinction between a code point and the corresponding abstract character is not pronounced in Unicode, but is evident for many other encoding schemes, where numerous may exist for a single code space.