JTC1/SC2/WG2 N2671
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Comments on N2665, Opinions on Encoding Tai Lue
Expert contributionPeter Constable, Microsoft
October 16, 2003
For consideration by JTC1/SC2/WG2, UTC
WG2/N2634 (=L2/03-321), N2242R, L2/99-243
WG2 members, UTC members

Document N2634 provides a complete proposal for encoding the Tai Lue(Xishuangbanna Dai) script. N26xx is a contribution from the China national bodyproviding comments on that proposal. This document provides comments on the Chinese
contribution.

Comments on individual points
The Chinese comments are listed in eight numbered points. The following comments arenumbered to correspond with the points in the Chinese contribution.
1. It is noted that the script in question is mainly used in China. This is undisputable. The
Chinese body hopes that N2242R, submitted by China at WG2 meeting #39, will berecognized as the original proposal. There were, in fact, earlier proposals or draft
proposals (as is noted in N2242R itself). What is important to determine, however, is notwhich proposal was first, but what proposal is the best for encoding the script.
Comparison of the two proposals, N2242R and N2634, is provided below.
2. It is noted that the number of characters in the two proposals is not the same. The isdue primarily to a difference in encoding model: N2242R analyzes certain text elements
into base + combining mark sequences while N2634 treats these as atomic characters(and does not propose separate combining marks). The only difference in terms ofrepresentable text is that N2242R omits the digit zero, which is attested in Tai Lue
documents, as shown in Figure 1:1

1This sample illustrates the existence of two alternate typeforms for the digit 1, both of which were listed
in L2/99-243.

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Figure 1. Tai Lue numbers 0—10 (LA1, p. 39)

Differences between N2242R and N2634 will be discussed further below.
3. It is noted that the typeface used in N2634 does not conform to the conventions andway of writing of the Tai Lue people. In fact, there are significant variations in typefaces,
as is demonstrated from samples taken from [LA1] and Jinxiang 1994:

Figure 2. Tai Lue type sample: LA1 (p. 73)

Figure 3. Tai Lue type sample: Jinxiang 1994 (p. 73)

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Figure 4. Tai Lue type sample: Jinxiang 1994 (cover)Jinxiang itself uses two very distinct faces: the cover uses a display face with rounded
typeforms, as are seen in the body text from [LA1], in contrast with the squared
typeforms of the body text in Jinxiang 1994. The body face in Jinxiang has significant
thick/thin variation in stroke widths, whereas the body face of [LA1] has fairly uniform
stroke widths.
The typeface used in the code chart of N2634 was developed in the USA, but was createdfor use in projects of the Chinese Academy of Social Sciences, Institute for Nationality
Studies. The design was intended to be original and to add qualities to aid in legibility,
but was guided strongly by the typeface used in [LA1]. It is the only digital typeface for
Tai Lue script that I know of, though I see no objection to use of a different face forpublished code charts, if another and better one is available.
4. The description of spelling rules in section E of N2634 is said to be unclear. It seems tome that the intent is made clear by the detailed examples in Table A of N2634:
orthographic syllables can include a consonant, vowel and tone mark, and the tone markis written following the consonant and any vowel marks.
The authors of N26xx inquire what the meaning is of the statement, “which are modified
with a hook showing that the inherent vowel is killed”. This refers to the seven syllablefinal consonant characters, which are common to both proposals: “”.
The authors of N26xx inquire about the meaning of the statement, “Tai Lue consonants
denote two tonal registers.” As is the case with other Tai scripts, such as Thai, Lao and
Lanna, characters for obstruent phonemes come in pairs: two characters have the same
segmental value, but differ with respect to the tonal values of syllables in with they are
the initial consonant. For instance, the Tai Lue characters “” and “” both represent
voiceless velar stop phonemes; in syllables with no written tone mark, syllables
beginning with “” have a high tone, whereas syllables beginning with “” have a falling
tone. Such pairings occur for all obstruent characters, and the two sets are referred to as“high class” and “low class” respectively.2 These facts are generally very familiar to
linguists studying Tai languages of China, Thailand, Laos, Myanmar and Vietnam.
5. It is stated that the examples in Table A of N2634 are invalid syllables in Tai Lue, andthat some of the phonetic transcriptions are wrong. There is no explanation as to what
precisely is incorrect in Table A. These criticisms should not have a bearing on thecharacter encoding proposal of N2634, however: all that is truly important from Table A
is the illustration of the encoding model by means of example character sequences andthe corresponding display.
2“High” and “low” are direct translations for the terms used in Tai languages to refer to these classes. For
instance, these classes are called  /suŋ ˥ / ‘high’ and  /tɛm 깻 / ‘low’.

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7. The authors of N26xx note that “Tai Lue scripts include New Tai Lue and Old Tai
Lue,” and that space should be provided in the BMP for both. It is not clear whether theauthors intend that both should be included in the same block.
In fact, space has been allocated in the range U+1A80–U+1AFF for Old Tai Lue, or “Old
Xishuangbanna Dai”, script under the name “Lanna”.3 This is appropriate since the older
tradition for writing Tai Lue uses a variant of the Lanna script, which originated in the
Lanna kingdom of northern Thailand and was adopted for writing various Tai languages
in surrounding regions, including Khun to the west, Tai Lue and perhaps Yong to thenorth, and northern varieties of Lao to the east. It would be inappropriate to merge theolder and newer writing systems into a single block as these are very distinct scripts withdifferent character inventories and significantly different behaviours.
8. It is noted that “‘Dai’ is an internationally standardized name in Pinyin for Dai
nationality and Dai script,” and on that basis it is requested that “Dai” rather than “Tai”
be used when encoding the script in the ISO/IEC 10646. It is true that “Dai” is the Pinyin
Romanization used in China for languages of this family and for the scripts associatedwith these languages. At the same time, “Tai” is the Romanization most widely usedinternationally by linguists specializing in this family of languages. Note, for instance,
the practice of the highly-esteemed Chinese linguist, Fang Kuei Li, who consistently used
“Tai” in his English-language publications.
I also note that the Dehong script was named “Tai Le” when encoded in ISO/IEC 10646.
That said, I do not feel this distinction in naming conventions is a serious issue, butconcede that it may be so for the Chinese national body.

Differences between proposals in N2242R and N2634
The preceding comments address individual points in N26xx. As noted in the commenton point 1, however, what is most important is to evaluate which proposal provides thebest approach to supporting the script. It is important, then, to identify substantive
differences between the proposals in N2242R and N2634.
N2242R did not propose appropriate names for characters, it did not explain encoding
model or suggest character properties, nor did it provide documentation illustrating
attested usage. This comparison will disregard those limitations and focus on substantive
differences of the proposed character encodings.
As noted, N2242R omits the digit zero, which clearly appears to be an oversight. N2242R
fails to provide certain key details, particularly whether vowel characters are considered
combining marks, always encoded after the consonant, or whether they are spacing letters,
preceding or following the consonant according to their visual order. I will assume theintent for N2242R was that they be considered combining marks.
The remaining differences between N2242R and N2634, then, are twofold: inventory ofcharacters, and the ordering of characters.

3

See the “Roadmap to the BMP,” at http://www.unicode.org/roadmaps/bmp/.

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Inventory of characters
The two proposals differ in character inventory due to a different encoding model withregard to certain text elements: N2242R uses a decomposed representation using
combining marks, while N2634 uses combining marks. The text elements for which theencoded representations differ are listed in Table 1:
Text element

Representation in N2242R

Representation in N2634

 xx81 + ◌ xxC8

 1981



◌






 xx92 + ◌ xxC8
 xx93 + ◌ xxC8
◌ xxA9 + ◌ xxA9
 xx82 + ◌ xxC6
 xx94 + ◌ xxC6
 xx83 + ◌ xxC6
 xx95 + ◌ xxC6
 xxC7 + ◌ xxC6

 19A3
 19A5◌ 19C2
 19A6
 19A7
 19A8
 19A9
 19DF

Table 1. Different encoding models for 9 text elements

This difference is not huge, and either encoding could be implemented successfully.
Overall, however, I find the advantages of N2634 sufficient to recommend its
representation for these text elements over that proposed by N2242R.
The “hat” that occurs over the graphemes for the high class voiced stops, “” does not
combine productively with any other characters. By analyzing these graphemes into base+ diacritic sequence, the pairing of characters in high class / low class pairs is broken, andvarious text processes are made slightly more complex as a result. For these reasons, theencoding of these three text elements proposed in N2634 is considered preferable.
By analyzing the vowel “◌” into a sequence of two “◌” characters, some text
processes will be made slightly more complex in that the structure for encoded
representation of orthographic syllables can now contain either one or two re-orderingvowels. Following the treatment of cognate vowel signs in other Indic scripts (Thai
U+0E41, Lao U+0EC1, Sinhala U+0DDB and Malayalam U+0D48), it is considered best
to encode this grapheme as a single character, as proposed in N2634.
The subjoined “va” sign occurs in Tai Lue text with four different consonants, “”,and with the abbreviation character “ ”. It is not subjoined productively with any otherconsonants in Tai Lue. Analyzing it as a separate combining mark might be advantageousshould the script ever be used for other languages that allow other labialized clusters.
N2242R might be considered preferable over N2634 in this regard, therefore. In Tai Luesources, the labialized forms are consistently listed as distinct graphemes. On the other
hand, it is not a requirement that graphemes be encoded as atomic characters. It should
also be noted that N2242R is slightly inconsistent in that the “va” sign is not analyzed in
the high-class grapheme “”. Also, I am not aware of any other languages that are
written with this script and that require additional labialized forms. The use of combining
marks in N2242R also implies the need for complex-rendering support in software
implementations, though this is also needed with the proposal in N2634 to deal withreordering combining marks. In conclusion, I favour the treatment of N2634 slightly, butcannot give a strong recommendation of one treatment of labialized forms over the other.
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Ordering of characters
There are differences of ordering between N2242R and N2634 in three different areas: (1)ordering of consonants, (2) ordering of diphthongs, and (3) ordering of syllable-final
consonants in relation to vowels.
1. Ordering of consonants. Consonants within Indic scripts, including Tai scripts,
are ordered according to several properties:4•

point of articulation: velar, palatal, retroflex,5 alveolar, labial•

manner of articulation: e.g. voiceless unaspirated, voiceless aspirated, nasal•

tone class: high, low

The two proposals agree on the ordering within any one of these properties, as doall source materials I have encountered. The proposals differ, however, withregard to the priority these properties have in relation to one another. Specifically,
they differ in whether tone class is given first priority or last priority. N2242R
makes tone class the primary factor, and so has all high-class consonants
preceding all low-class consonants. N2634, however, considers tone class last,and so interleaves high- and low-class consonants on the basis of pairs having
common segmental values.
The difficulty in determining the correct order is that source materials do notalways make absolutely clear how tone class should be considered in relation toother consonant properties. It is not uncommon to display consonant charts withthe high and low consonants listed in separate columns, but such charts do notmake clear how tone should be considered in ordering, and so the division of toneclasses in these charts should not necessarily be understood to imply anythingwith respect to collation. For instance, [LA1] contains such a chart, shown in
Figure 5:4Some collation conventions may divide manner of articulation into multiple factors; e.g., obstruent vs.
nasal, and stop vs. fricative; or voiceless vs. voiced vs. nasal, and with or without aspiration.
5
Tai languages do not have retroflex consonant phonemes, though some Tai scripts have maintained
characters corresponding to retroflex consonants in Pali or Sanskrit. Tai Lue does not do so, however.
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Figure 5. Tai Lue consonant chart: high and low class consonants listed separately (LA1, p. 7)

This same book, which is a literacy primer used for Tai Lue students in schools in
the Xishuangbanna region, teaches the consonants with high- and low-classconsonants interleaved, however. Unfortunately, it is not consistent in how it does
this: the first eight consonants consider tone class after manner of articulation:

Figure 6. Tai Lue consonants in LA1: glottal and velar consonants (LA1, p. 1)

The ordering for the remaining consonants, however, considers tone class after
point of articulation but before manner of articulation:

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Figure 7. Tai Lue consonants in LA1: palatal and alveolar consonants (pp. 2–3)

It seems clear, though, that consonants are not taught using an order that considers
tone class first (listing all high-class consonants before any low-class consonants).
Also, in no case that I am aware of do the sort orders of other Tai scripts consider
tone class before other consonant properties, point of articulation in particular.
Thus, it cannot be said for certain that the ordering of consonants in N2634 is theestablished conventional order. On the other hand, the ordering in N2242R, which
considers tone class before point or manner of articulation, is not clearly attested
in Tai Lue sources I have seen, and is unusual for Tai scripts.
2. Ordering of diphthongs. As noted in N2660, I consider the internal ordering ofdiphthongs in N2634 to be wrong, and suggest that IY should follow all otherdiphthongs. I concur, therefore, with the Chinese comments in this regard.
3. Ordering of syllable-final consonants in relation to vowels. N2242R lists
syllable-final consonant characters in the middle of the vowel characters, after “”/ai/ and before “” /aːi/. In contrast, N2634 lists the syllable-final consonant
characters before any vowels.
The ordering of N2242R in this respect is unusual, and not supported in any
source materials I have seen. For a given initial consonant C, it is unclear fromsources if there are established conventions as to whether a syllable written in theform C + V should sort before or after a syllable in the form C + Cf; for example, <  <  <  <  versus  <  <  <  < . Syllable rhyme
charts are not clear or consistent in this regard: the chart in Figure 8 indicates thatC + V syllables precede C + Cf or C + V + Cf syllables. The chart in Figure 9 lists
syllable-final consonants after vowels, but does not make clear what the orderingof syllable rhymes should be. The chart in Figure 10 shows the same ordering ofclosed rhymes as the chart in Figure 8, but provides no information regarding
open syllables in relation to closed syllables.
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Figure 8. Tai Lue syllable rhyme chart: (LA1, p. 36)

Figure 9. Tai Lue syllable rhyme chart: (SCEM, p. 73)

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Figure 10. Tai Lue syllable rhyme chart: (PSCC, p. 166)

It is clear, however, that C + Cf syllables precede C + V + Cf syllables. It also
seems clear that the order suggested by N2242R with C + Cf syllables after someC + V syllables and before others, e.g.,  <  <  <  < , is not
generally used.
Thus, while there is some uncertainty regarding conventional ordering of rhymes,
there is some evidence to support the placement of syllable-final consonants
before vowels, as in N2634, though the evidence equally supports placement ofsyllable-final consonants after all vowels; but I have not seen any evidence tosupport placement of syllable-final consonants after some vowels but before
others, as in N2242R.
In summary, there is variation among source materials regarding collation order.
Moreover, Tai Lue sorting involves considerations that go beyond mere code point
ordering of characters. Nevertheless, with the exception of the internal order ofdiphthongs, I consider there to be good basis for adopting the ordering of characters in
N2634.

References[SCEM]

中国社会科学院民族硏究所, 国家民族事务委员会文化宣传司(Zhongguo
shehui kexueyuan minzu yianjiusuo, guojia minzu shiwu weiyuanhui wenhua
xuanchuansi = Chinese Academy of Social Sciences, Institute for Nationality
Studies; Department of Cultural Propagation, State Ethnic Affairs
Commission). 1991. 中国少数民族文字 (Zhongguo shaoshu minzu wenzi =Scripts of Chinese Ethnic Minorities). 北京 (Beijing): 中国藏学出版社(Zhongguo zangxue chubanshe = China Tibetan Studies Publishing House).

[PSCC]

戴庆厦 许寿椿 高喜奎 主编 (Dai Qingsha, Xu Shouchuan, Gao Xikui,
editors-in-chief). 1991. 中国各民族文字与电脑信息处理 (Zhongguo ge
minzu wenzi yu diannao xinxi chuli = Processing the scripts of China on thecomputer). 北京 (Beijing): 中央民族学院出版社 (Zhongyang minzu
xueyuan chubanshe = Central Nationalities Institute Publishing House).

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 (搜集整理者 = Dao Jinxiang). 1994.  (古傣语词语译翻 = Dictionary of ancient Dai words and expressions). 昆明 (Kunming): (云南民族出版社出版 = Yunnan
Nationalities Press).
[LA1]

西双版纳州教育局编 (Xishuangbanna Prefectural Education Bureau). 1980.
,    (语 文, 第一册 = Language arts, book 1). (西双版
纳傣文小学课本 = Xishuangbanna Dai primary school textbook.) 昆明(Kunming):云南民族出版社出版 (Yunnan Nationalities Press).

L2/99-243 Constable, Peter. 1999. “Proposal for encoding New Tai Lue script inUnicode/ISO-IEC 10646.”
N2242R

China. 2000. “Proposal for encoding Xishuang Banna Dai script on BMP of
ISO/IEC 10646.”

N2634

Eversion, Michael. 2003. “Proposal to encode the Tai Lue script in the BMPof the UCS.”

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