Definition
The notion of a code point is used for abstraction, to distinguish both:
- the number from an encoding as a sequence of bits, and
- the abstract character from a particular graphical representation (glyph).
This is because one may wish to make these distinctions:
- encode a particular code space in different ways, or
- display a character via different glyphs.
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) binary numbers, 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 code pages may exist for a single code space.
Read more about this topic: Code Point
Famous quotes containing the word definition:
“Mothers often are too easily intimidated by their children’s negative reactions...When the child cries or is unhappy, the mother reads this as meaning that she is a failure. This is why it is so important for a mother to know...that the process of growing up involves by definition things that her child is not going to like. Her job is not to create a bed of roses, but to help him learn how to pick his way through the thorns.”
—Elaine Heffner (20th century)
“Scientific method is the way to truth, but it affords, even in
principle, no unique definition of truth. Any so-called pragmatic
definition of truth is doomed to failure equally.”
—Willard Van Orman Quine (b. 1908)
“The very definition of the real becomes: that of which it is possible to give an equivalent reproduction.... The real is not only what can be reproduced, but that which is always already reproduced. The hyperreal.”
—Jean Baudrillard (b. 1929)