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Unicode compatibility characters
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<p>In <a href="/facts/Unicode/DDu3MfPV">Unicode</a> and the <a href="/facts/Universal_Character_Set/7Tn6LPLw">UCS</a>, a compatibility character is a character that is encoded solely to maintain <a href="/facts/Round-trip_format_conversion/q9ssQvUP">round-trip convertibility</a> with other, often older, standards. As the Unicode Glossary says: </p> <blockquote> <p>A character that would not have been encoded except for compatibility and round-trip convertibility with other standards </p> </blockquote> <p>Although <i>compatibility</i> is used in names, it is not marked as a property. However, the definition is more complicated than the glossary reveals. One of the properties given to characters by the Unicode consortium is the characters' decomposition or <a href="/facts/Compatibility_decomposition/yXUtR6GW">compatibility decomposition</a>. Over five thousand characters do have a compatibility decomposition mapping that compatibility character to one or more other UCS characters. By setting a character's decomposition property, Unicode establishes that character as a compatibility character. The reasons for these compatibility designations are varied and are discussed in further detail below. The term <i>decomposition</i> sometimes confuses because a character's decomposition can, in some cases, be a singleton. In these cases the decomposition of one character is simply another approximately (but not canonically) <a href="/facts/Unicode_equivalence/yXUtR6GW">equivalent</a> character. </p>