combining diacritical mark

In digital typography, combining characters are characters  that are intended to modify other characters. The most common combining characters in the Latin script are the combining diacritical marks (including combining accents). Unicode also contains many precomposed characters, so that in many cases it is possible to use both combining diacritics and precomposed characters, at the user's or application's choice. This leads to a requirement to perform Unicode normalization before comparing two Unicode strings and to carefully design encoding converters to correctly map all of the valid ways to represent a character in Unicode to a legacy encoding to avoid data loss. In Unicode, the main block of combining diacritics for European languages and the International Phonetic Alphabet is U+0300–U+036F. Combining diacritical marks are also present in many other blocks of Unicode characters. In Unicode, diacritics are always added after the main character. It is thus possible to add several diacritics to the same character, although as of 2006, few applications support correct rendering of such combinations: Nisus Writer is a word processor notable for good handling of combining diacritics even when no predefined glyphs are present in the font.
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