Specials (Unicode block)

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Specials is a short Unicode block of characters put at the very end of the Basic Multilingual Plane, at U+FFF0–FFFF. Of these 16 code points, five have been used since Unicode 3.0:

• U+FFF9 INTERLINEAR ANNOTATION ANCHOR, marks start of annotated text
• U+FFFA INTERLINEAR ANNOTATION SEPARATOR, marks start of annotating character(s)
• U+FFFB INTERLINEAR ANNOTATION TERMINATOR, marks end of annotation block
• U+FFFC  OBJECT REPLACEMENT CHARACTER, placeholder in the text for another unspecified object, for example in a compound document.
• U+FFFD � REPLACEMENT CHARACTER used to replace an unknown, unrecognized, or unrepresentable character
• U+FFFE <noncharacter-FFFE> not a character.
• U+FFFF <noncharacter-FFFF> not a character.

FFFE and FFFF are not unused in the usual way, but guaranteed not to be Unicode characters at all. They can be used to guess a text's scheme, since any text using these is not a correctly encoded Unicode text. Unicode's U+FEFF BYTE ORDER MARK character can be put at the start of a Unicode text to signal its endianness: a program reading such a text and finding 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.^[3]

1. ↑ "Unicode character database". The Unicode Standard. Retrieved 2016-07-09.
2. ↑ "Enumerated Versions of The Unicode Standard". The Unicode Standard. Retrieved 2016-07-09.
3. ↑ "3.8: Block-by-Block Charts" (PDF). The Unicode Standard. version 1.0. Unicode Consortium.