Unicode equivalence

Unicode equivalence is the specification by the <a href="/facts/Unicode/DDu3MfPV">Unicode</a> <a href="/facts/Character_(computing)/X2zKLFFB">character</a> encoding standard that some sequences of <a href="/facts/Code_point/R184ugJX">code points</a> represent essentially the same character. This feature was introduced in the standard to allow compatibility with pre-existing standard <a href="/facts/Character_set/ShJHIMoA">character sets</a>, which often included similar or identical characters.
<a href="/facts/Unicode/DDu3MfPV">Unicode</a> provides two such notions, <a href="/facts/Canonical_form/K2jhB44k">canonical</a> equivalence and compatibility. <a href="/facts/Code_point/R184ugJX">Code point</a> sequences that are defined as canonically equivalent are assumed to have the same appearance and meaning when printed or displayed. For example, the code point U+006E n <a href="/facts/N/0CEs8314">LATIN SMALL LETTER N</a> followed by U+0303 ◌̃ <a href="/facts/Combining_character/nH8SFbIL">COMBINING TILDE</a> is defined by Unicode to be canonically equivalent to the single code point U+00F1 ñ LATIN SMALL LETTER N WITH TILDE of the <a href="/facts/Spanish_alphabet/DNP7QG9J">Spanish alphabet</a>). Therefore, those sequences should be displayed in the same manner, should be treated in the same way by applications such as <a href="/facts/Alphabetical_order/oKu6Ke37">alphabetizing</a> names or <a href="/facts/String_searching/RCvwDRle">searching</a>, and may be substituted for each other. Similarly, each <a href="/facts/Hangul/prUQxzfJ">Hangul</a> syllable block that is encoded as a single character may be equivalently encoded as a combination of a leading conjoining jamo, a vowel conjoining jamo, and, if appropriate, a trailing conjoining jamo.
Sequences that are defined as compatible are assumed to have possibly distinct appearances, but the same meaning in some contexts. Thus, for example, the code point U+FB00 (the <a href="/facts/Typographic_ligature/urMIGfmN">typographic ligature</a> "ﬀ") is defined to be compatible—but not canonically equivalent—to the sequence U+0066 U+0066 (two Latin "f" letters). Compatible sequences may be treated the same way in some applications (such as <a href="/facts/Sorting/olGzsItY">sorting</a> and <a href="/facts/Index_(database)/TRqmk9It">indexing</a>), but not in others; and may be substituted for each other in some situations, but not in others. Sequences that are canonically equivalent are also compatible, but the opposite is not necessarily true.
The standard also defines a <a href="/facts/Text_normalization/H56wc4GH">text normalization</a> procedure, called Unicode normalization, that replaces equivalent sequences of characters so that any two texts that are equivalent will be reduced to the same sequence of code points, called the normalization form or normal form of the original text. For each of the two equivalence notions, Unicode defines two normal forms, one fully composed (where multiple code points are replaced by single points whenever possible), and one fully decomposed (where single points are split into multiple ones).

Unicode equivalence open-in-new

Unicode equivalence