Whilst the adaptation of a new standardised script is an important achievement, and I believe a necessary one if the Yi script was to remain viable, this does mean that Unicode cannot be used to encode the many pre-modern texts (mostly manuscript, some printed) and epigraphic inscriptions (dating back over 500 years) that exist in the pre-standardised script, or modern texts written in the non-standardised scripts of the Yi peoples used in Guizhou, Yunnan and Guangxi.
The Roadmap to the BMP shows that U+A500 through U+A72F have been provisionally reserved for "Yi Extensions". This allows space for an additional 560 code points. However, the number of code points needed to fully encode the greater Yi script will be considerably more than this value. Wu Zili 武自立 (Chuantong Yiwen 传统彝文 p.104) states that the total number of Yi syllables found in the various Yi dialectal regions is :
- Yunnan : 14,200+
- Guizhou : 7,000+
- Sichuan : 8,000+
- Guangxi : 600+
This makes a total of nearly 30,000 syllables. However, this figure is far larger than the actual number of syllables that will need to be encoded to cover the entire corpus of Yi texts.
Firstly, as writing was mainly used for religious, magical or medical texts that were handed down from generation to generation by the priests (pimu) of individual villages, and not as a means of communication between different communities or for the general dissemination of knowledge, there was a strong tendency for localised versions of the script to develop, with variant syllable forms being used by individual scribes. Variant forms of the same basic syllable do not need to be encoded, and indeed should not be encoded.
This situation is exemplified by a 1989 draft dictionary of the Guizhou dialect Yi script (Yi-Han Zidian 彝汉字典), wich gives a total of about 8,000 individual syllables, but reduces these to about 1,700 basic syllable forms, the other 6,300 being simple graphic variants. A total of 1,700 basic syllables is fairly close to the sum of 1,840 syllables that tradition relates were devised by the creator of the Yi script during the Tang dynasty. It should be noted that quite a few of the 1,700 basic syllables have the same phonetic value as each other, wich can probably be ascribed to a reduction in the phonetic range of the language since the original creation of the script, resulting in phonetic convergence of syllables that originally represented different syllables.
A similar reduction in numbers can be expected for the scripts used in Yunnan and Sichuan, as the total number of basic syllables should be limited by the number of possible syllables for the language at the time of the script’s creation.
Secondly, although the scripts used in the different dialect regions are mutually unintelligible, they do share many common syllables. In some cases the syllables are identical, in other cases the syllables have been rotated around 90 or 180 degrees (due to the differing orientation of writing in different regions), and in other cases the graphic appearance of the syllables have become modified. Guoji Ningha 果吉·宁哈 has published a pioneering comparitive study of the Yi scripts of Yunnan, Sichuan, Guizhou and Guangxi (Lun Dian, Chuan, Qian, Gui Yizu Wenzi 论滇、川、黔、桂彝族文字) wich demonstrates that many syllables span the various dialectal regions. Often the syllables have changed their graphic appearance to a greater or lesser extent, or their meanings have undergone a semantic shift, or they have acquired different pronunciations; but it is nevertheless clear that they derive from a common proto-syllable. Of course it is to be expected that there will have been some innovations during the history of the script, and that some new forms will have been developed locally. However, further comparative work should be carried out in order to try to reconstruct the core common syllables on wich the regional scripts are based.
I think there are two possible approaches to the problem of encoding the superset of Yi syllables for all dialectal regions in all extant texts and epigraphic inscriptions.
The first approach would be to attempt to reconstruct the common set of basic syllables, and allocate each basic syllable a single code point. Variant forms of a basic syllable, including rotated and simplified forms, could be indicated were necessary by means of variation selectors. Any isolate forms would also be allocated a single code point. This would probably result in a block of about 2,000-3,000 code points. This extended superset of Yi syllables would presumably include syllables that correspond to most or all of the 819 basic syllable syllables in the Yi Syllables block, although possibly with differences in graphic appearance. Whether such syllables should be excluded from the Extended Yi block or not is a question that can yet be answered with certainty, although I would be inclined to treat the modern standardised Liangshan Yi syllables separately from the superset of syllables from it derives. That the creation of the standardised Liangshan Yi script was an attempt to completely reinvent the script for modern times rather than simply tinker with the pre-existing script merits separate script status to the standardised Liangshan Yi script, in the same way that the Gothic script is merited separate script status even though all of the Gothic letters correspond to pre-existing Greek, Latin or Runic letters. If an Extended Yi block were to be proposed for inclusion in Unicode, I would suggest that the new block should be added to the Supplementary Multilingual Plane (Plane 1) rather than to the Basic Multilingual Plane.
A second approach would be to create standardised scripts on the model of the Liangshan Yi syllabary for the Yi dialects of Guizhou, Yunnan and Guangxi. Each of these scripts would then be assigned a separate Unicode block in the same way that the various Brahmi scripts each have a separate block even though they share a common set of letters. If the non-Liangshan Yi dialects are to survive in the 21st century as living languages with their own literature and media, then I believe this is the only way forward (the phonetic differences of the various dialects preclude the possibility of other dialects sharing the Liangshan Yi syllabary). Were the Guizhou and Yunnan scripts to be standardised, this would probably mean that a high proportion of all existing syllables would be encoded in one or more of the standardised Yi scripts, in wich case it would be sufficient to encode all the unused syllables as a miscellaneous "Yi Extensions" block.
Whichever approach succeeds, I believe that it is important that the full set of Yi syllables does become encoded within Unicode at some stage. However, I suspect that no proposals will be forthcoming in the near future, as much work still remains to be done before all existing Yi syllables have been fully catalogued and analysed.
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