Specials | |
---|---|
Range | U+FFF0..U+FFFF (16 code points) |
Plane | BMP |
Scripts | Common |
Assigned | 5 code points |
Unused | 9 reserved code points 2 non-characters |
Unicode version history | |
1.0.0 (1991) | 1 (+1) |
2.1 (1998) | 2 (+1) |
3.0 (1999) | 5 (+3) |
Unicode documentation | |
Code chart ∣ Web page | |
Note: [1][2] |
Specials is a short Unicode block of characters allocated at the very end of the Basic Multilingual Plane, at U+FFF0–FFFF. Of these 16 code points, five have been assigned since Unicode 3.0:
U+FFFE <noncharacter-FFFE> and U+FFFF <noncharacter-FFFF> are noncharacters, meaning they are reserved but do not cause ill-formed Unicode text. Versions of the Unicode standard from 3.1.0 to 6.3.0 claimed that these characters should never be interchanged, leading some applications to use them to guess text encoding by interpreting the presence of either as a sign that the text is not Unicode. However, Corrigendum #9 later specified that noncharacters are not illegal and so this method of checking text encoding is incorrect.[3] An example of an internal usage of U+FFFE is the CLDR algorithm; this extended Unicode algorithm maps the noncharacter to a minimal, unique primary weight.[4]
Unicode's U+FEFF ZERO WIDTH NO-BREAK SPACE character can be inserted at the beginning of a Unicode text to signal its endianness: a program reading such a text and encountering 0xFFFE would then know that it should switch the byte order for all the following characters.
Its block name in Unicode 1.0 was Special.[5]
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