Unicode compatibility characters: Difference between revisions

Revision as of 01:36, 7 February 2014

Revision as of 06:35, 15 May 2014

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Roman numeral One Thousand actually has a third character representing a third form or glyph for the same semantic unit: One Thousand C D (ↀ U+2180). From this glyph, one can see where the practice of using a Latin M may have arisen. Strangely, though Unicode unifies the [[sign-value notation|sign-value]] Roman numerals with the very different{{citation needed|date=May 2009}} (though visually similar) Latin letters, the Indic Arabic [[place-value]] (positional) decimal digit numerals are repeated 24 times (a total of 240 code points for 10 numerals) throughout the UCS without any relational or decomposition mapping between them.

The presence of these 167 semantically distinct though visually similar characters (plus the borderline 11 Hebrew and Greek letter based symbols and the 6 measurement unit symbols) among the decomposable characters complicates the topic of compatibility characters. The Unicode standard discourages the use of compatibility characters by content authors. However, in certain specialized areas, these characters are important and quite similar to other characters that have not been included among the compatibility characters. For example, in certain academic circles the use of Roman numerals as distinct from Latin letters that share the same glyphs would be no different thanfrom the use of Cuneiform numerals or ancient Greek numerals. Collapsing the Roman numeral characters to Latin letter characters eliminates a semantic distinction. A similar situation exists for phonetic alphabet characters that use subscript or superscript positioned glyphs. In the specialized circles that use phonetic alphabets, authors should be able to do so without resorting to rich text protocols. As another example the keyword 'circle' compatibility characters are often used for describing the game [[Go (game)|Go]]. However, these uses of the compatibility characters constitute exceptions where the author has a special reason to use the otherwise discouraged characters.

== Compatibility Blocks ==