Unicode Explained

Here the word “private” has a wider meaning than in common language. For example,

two large public institutions could agree on the use of some private use code points for

their information interchange. You could use private use code points even in data that

you distribute in public, as long as you make it clear that the interpretation and pro-

cessing of the data requires knowledge about special definitions you have made.

You should not use unassigned code points even for internal purposes like bookkeeping

or “sentinels” such as indicators of end of character data or separators between blocks

of character data. For such purposes, you can often use code points assigned to control

characters or declared as noncharacters.

Do not use unassigned code points for anything. If you need a code point

for a character that cannot be expressed in Unicode (yet), use private

use code points.

Unicode Terms

The Unicode standard and related documents contain a large number of special terms,

often consisting of common words in highly specialized meanings. In this book, the

presentation of the terms has been spread across the material, into contexts where the

terms can be illustrated and exemplified. To check the meaning of a particular term, it

is therefore simplest to consult the index.

In this section, some special Unicode terms are presented. The terms refer to concepts

that don’t quite belong to the core of