Privateuse

Private use refers to a set of Unicode code points that are intentionally not assigned standard characters by the Unicode Consortium. These code points are reserved for private use by individuals, organizations, or software systems to define their own characters, symbols, or scripts. Because they have no universal meaning, the interpretation of private-use code points depends on an agreed mapping within a given environment.

The Unicode Private Use Areas are divided into three blocks. The Basic Multilingual Plane Private Use Area runs from U+E000 to U+F8FF and contains about 6,400 code points. There are also supplementary private use blocks: Supplemental Private Use Area-A from U+F0000 to U+FFFFD and Supplemental Private Use Area-B from U+100000 to U+10FFFD, each providing an additional set of private-use code points. These areas are intended for private use only and must not be relied upon for interoperable text exchange without a shared agreement on the meaning of the points.

Usage and considerations include the following. Private-use code points are commonly employed by fonts to embed unique glyphs, by firms to encode proprietary symbols, or by linguists and authors for nonstandard or fictional scripts. Since there is no universal assignment, text containing private-use characters is not portable across systems unless the same private mapping is maintained. Software must avoid assuming any specific shape or meaning for private-use code points, and data interchange should ideally carry external documentation about the private mappings. In practice, developers use private use with caution, documenting the intended interpretation and limiting public distribution to contexts where the mapping is known and shared.