Combining character

Combining diacritical marks are Unicode characters that are intended to modify other characters (see Diacritic). The main block of combining diacritics is U+0300 — U+036F. They are also present in many other blocks of Unicode characters. In Unicode, diacritics are always added after the main character. It is possible to add several diacritics to the same character.

Unicode also contains a lot of precomposed characters. So in many cases it is possible to use both combining diacritics and precomposed characters, at the user's choice.

On most computer systems today, the combining diacritics are added to main characters with simple superposition of glyphs. The results are usually far from perfect. The better strategy is to use algorithms that allow to select precomposed glyphs for such combinations. This is possible with OpenType fonts.