Editing Unicode (section)

=== Indic scripts ===
{{further|Tamil All Character Encoding}}
[[Indic script]]s such as [[Tamil script|Tamil]] and [[Devanagari]] are each allocated only 128 code points, matching the [[ISCII]] standard. The correct rendering of Unicode Indic text requires transforming the stored logical order characters into visual order and the forming of ligatures (also known as conjuncts) out of components. Some local scholars argued in favor of assignments of Unicode code points to these ligatures, going against the practice for other writing systems, though Unicode contains some Arabic and other ligatures for backward compatibility purposes only.<ref>{{Cite web |title=Arabic Presentation Forms-A |url=https://www.unicode.org/charts/PDF/UFB50.pdf |access-date=20 March 2010}}</ref><ref>{{Cite web |title=Arabic Presentation Forms-B |url=https://www.unicode.org/charts/PDF/UFE70.pdf |access-date=20 March 2010}}</ref><ref>{{Cite web |title=Alphabetic Presentation Forms |url=https://www.unicode.org/charts/PDF/UFB00.pdf |access-date=20 March 2010}}</ref> Encoding of any new ligatures in Unicode will not happen, in part, because the set of ligatures is font-dependent, and Unicode is an encoding independent of font variations. The same kind of issue arose for the [[Tibetan script]] in 2003 when the [[Standardization Administration of China]] proposed encoding 956 precomposed Tibetan syllables,<ref>{{Cite web |date=2 December 2002 |title=Proposal on Tibetan BrdaRten Characters Encoding for ISO/IEC 10646 in BMP |url=https://www.unicode.org/L2/L2002/02455-n2558-tibetan.pdf}}</ref> but these were rejected for encoding by the relevant ISO committee ([[ISO/IEC JTC 1/SC 2]]).<ref>{{Cite web |first1=V. S. |last1=Umamaheswaran |date=7 November 2003 |title=Resolutions of WG 2 meeting 44 |url=https://www.unicode.org/L2/L2003/03390r-n2654.pdf |at=Resolution M44.20}}</ref>

[[Thai alphabet]] support has been criticized for its ordering of Thai characters. The vowels เ, แ, โ, ใ, ไ that are written to the left of the preceding consonant are in visual order instead of phonetic order, unlike the Unicode representations of other Indic scripts. This complication is due to Unicode inheriting the [[TIS-620|Thai Industrial Standard 620]], which worked in the same way, and was the way in which Thai had always been written on keyboards. This ordering problem complicates the Unicode collation process slightly, requiring table lookups to reorder Thai characters for collation.<ref name="dw2001" /> Even if Unicode had adopted encoding according to spoken order, it would still be problematic to collate words in dictionary order. E.g., the word {{Wikt-lang|th|แสดง}} {{IPA|th|sa dɛːŋ|}} "perform" starts with a consonant cluster "สด" (with an inherent vowel for the consonant "ส"), the vowel แ-, in spoken order would come after the ด, but in a dictionary, the word is collated as it is written, with the vowel following the ส.