Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...

, two

glyph A glyph () is any kind of purposeful mark. In typography, a glyph is "the specific shape, design, or representation of a character". It is a particular graphical representation, in a particular typeface, of an element of written language. A g ...

s are said to be Z-variants (often spelled zVariants) if they share the same etymology but have slightly different appearances and different Unicode

code point In character encoding terminology, a code point, codepoint or code position is a numerical value that maps to a specific character. Code points usually represent a single grapheme—usually a letter, digit, punctuation mark, or whitespace—but ...

s. For example, the Unicode characters U+8AAA 說 and U+8AAC 説 are Z-variants. The notion of Z-variance is only applicable to the "

CJKV In internationalization, CJK characters is a collective term for the Chinese, Japanese, and Korean languages, all of which include Chinese characters and derivatives in their writing systems, sometimes paired with other scripts. Collectively, th ...

scripts"—Chinese, Japanese, Korean and Vietnamese—and is a subtopic of

Han unification Han unification is an effort by the authors of Unicode and the Universal Character Set to map multiple character sets of the Han characters of the so-called CJK languages into a single set of unified characters. Han characters are a featur ...

Differences on the Z-axis

The Unicode philosophy of code point allocation for CJK languages is organized along three "

axes Axes, plural of '' axe'' and of '' axis'', may refer to * ''Axes'' (album), a 2005 rock album by the British band Electrelane * a possibly still empty plot (graphics) See also * Axess (disambiguation) *Axxess (disambiguation) Axxess may refer to ...

." The X-axis represents differences in semantics; for example, the Latin capital A (U+0041 A) and the Greek capital alpha (U+0391 Α) are represented by two distinct code points in Unicode, and might be termed "X-variants" (though this term is not common). The Y-axis represents significant differences in appearance though not in semantics; for example, the traditional Chinese character ''māo'' "cat" (U+8C93 貓) and the simplified Chinese character (U+732B 猫) are Y-variants. The Z-axis represents minor typographical differences. For example, the Chinese characters (U+838A 莊) and (U+8358 荘) are Z-variants, as are (U+8AAA 說) and (U+8AAC 説). The glossary at ''Unicode.org'' defines "Z-variant" as "Two CJK unified ideographs with identical semantics and unifiable shapes," where "unifiable" is taken in the sense of Han unification. Thus, were Han unification perfectly successful, Z-variants would not exist. They exist in Unicode because it was deemed useful to be able to "round-trip" documents between Unicode and other CJK encodings such as

Big5 Big-5 or Big5 is a Chinese character encoding method used in Taiwan, Hong Kong, and Macau for traditional Chinese characters. The People's Republic of China (PRC), which uses simplified Chinese characters, uses the GB 18030 character se ...

and CCCII. For example, the character 莊 has CCCII encoding 21552D, while its Z-variant 荘 has CCCII encoding 2D552D. Therefore, these two variants were given distinct Unicode code points, so that converting a CCCII document to Unicode and back would be a lossless operation.

Confusion

There is some confusion over the exact definition of "Z-variant." For example, in an

Internet Draft An Internet Draft (I-D) is a document published by the Internet Engineering Task Force (IETF) containing preliminary technical specifications, results of networking-related research, or other technical information. Often, Internet Drafts are int ...

(of ) dated 2002, one finds "no" (U+4E0D 不) and (U+F967 不︀) described as "font variants," the term "Z-variant" being apparently reserved for interlanguage pairs such as the

Mandarin Chinese Mandarin (; ) is a group of Chinese (Sinitic) dialects that are natively spoken across most of northern and southwestern China. The group includes the Beijing dialect, the basis of the phonology of Standard Chinese, the official language ...

"rabbit" (U+5154 兔) and the Japanese "rabbit" (U+514E 兎). However, the

Unicode Consortium The Unicode Consortium (legally Unicode, Inc.) is a 501(c)(3) non-profit organization incorporated and based in Mountain View, California. Its primary purpose is to maintain and publish the Unicode Standard which was developed with the intentio ...

's Unihan database treats both pairs as Z-variants.

References

{{Unicode navigation Character encoding Unicode Computer-related introductions in 1991