A better (but harder to implement) design is to preserve the original bytes, including the error, and only convert to the replacement when displaying the text. Since the replacement is the same for all errors this makes it impossible to recover the original character. The whole string now displays like this: "f�r".Ī poorly implemented text editor might save the replacement in UTF-8 form the text file data will then look like this: 0圆6 0圎F 0xBF 0xBD 0x72, which will be displayed in ISO-8859-1 as "f�r" (this is called mojibake).
#MICROSOFT EQUATION EDITOR 3.0 MISSING CODE#
Therefore, a text editor could replace this byte with the replacement character symbol to produce a valid string of Unicode code points. The first and last byte are valid UTF-8 encodings of ASCII, but the middle byte ( 0xFC) is not a valid byte in UTF-8. This file is now opened with a text editor that assumes the input is UTF-8. It is usually seen when the data is invalid and does not match any character:Ĭonsider a text file containing the German word für (meaning 'for') in the ISO-8859-1 encoding ( 0圆6 0xFC 0x72). It is used to indicate problems when a system is unable to render a stream of data to a correct symbol. The replacement character � (often displayed as a black rhombus with a white question mark) is a symbol found in the Unicode standard at code point U+FFFD in the Specials table. Its block name in Unicode 1.0 was Special. Unicode's U+FEFF BYTE ORDER MARK 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. They can be used to guess a text's encoding scheme, since any text containing these is by definition not a correctly encoded Unicode text.
U+FFFD � REPLACEMENT CHARACTER used to replace an unknown, unrecognized, or unrepresentable characterįFFE and FFFF are not unassigned in the usual sense, but guaranteed not to be Unicode characters at all.U+FFFC  OBJECT REPLACEMENT CHARACTER, placeholder in the text for another unspecified object, for example in a compound document.U+FFFB INTERLINEAR ANNOTATION TERMINATOR, marks end of annotation block.
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