Unicode Trivia U+0DA5

Codepoint: U+0DA5 "SINHALA LETTER TAALUJA SANYOOGA NAAKSIKYAYA"
Block: U+0D80..0DFF "Sinhala"

As  Richard Gillam says in "Unicode Demystified" (2003), page 330:

The Unicode Sinhala block runs from U+0D80 to U+0DFF. It does not follow the ISCII order, partly because the ISCII standard doesn't include a code page for Sinhala and partly because Sinhala includes a lot of sounds (and, thus, letters) that aren't present in any of the Indian scripts. The basic setup of the block is the same: anusvara and visarga first, followed by independent vowels, consonants, dependent vowels, and punctuation. Unlike in the ISCII-derived blocks, the al-lakuna (virama) precedes the dependent vowels, rather than following them.

The order of codepoints (or of text made up of codepoints) can be thought of in at least three ways:

1. The order of codepoints within the character set, e.g. Unicode ("codepoint order")
2. The order of letters in an 'alphabet', e.g. Sinhala abugida ("alphabet order")
3. The typical order of words in a language's dictionary ("collation order")

As an example, we'll consider the letters (and only the standalone letters) from the Sinhala block (U+0D80..0DFF).

In codepoint order, these are:

• 18 independent vowels (U+0D85..0D96)
• 41 consonants (U+0D9A..0DC6)

The alphabet order (according to sites such as Omniglot) is the same as the codepoint order. This was presumably a factor in the ordering of the codepoints when the block was added to Unicode 3.0 in 1999.

However, in "collation order" these 59 letters (along with their Sinhalese and Romanized phonetic names) are:

1. U+0D85 = "අ" = AYANNA = vowel a
2. U+0D86 = "ආ" = AAYANNA = vowel aa
3. U+0D87 = "ඇ" = AEYANNA = vowel ae
4. U+0D88 = "ඈ" = AEEYANNA = vowel aae
5. U+0D89 = "ඉ" = IYANNA = vowel i
6. U+0D8A = "ඊ" = IIYANNA = vowel ii
7. U+0D8B = "උ" = UYANNA = vowel u
8. U+0D8C = "ඌ" = UUYANNA = vowel uu
9. U+0D8D = "ඍ" = IRUYANNA = vowel vocalic r
10. U+0D8E = "ඎ" = IRUUYANNA = vowel vocalic rr
11. U+0D8F = "ඏ" = ILUYANNA = vowel vocalic l
12. U+0D90 = "ඐ" = ILUUYANNA = vowel vocalic ll
13. U+0D91 = "එ" = EYANNA = vowel e
14. U+0D92 = "ඒ" = EEYANNA = vowel ee
15. U+0D93 = "ඓ" = AIYANNA = vowel ai
16. U+0D94 = "ඔ" = OYANNA = vowel o
17. U+0D95 = "ඕ" = OOYANNA = vowel oo
18. U+0D96 = "ඖ" = AUYANNA = vowel au
19. U+0D9A = "ක" = ALPAPRAANA KAYANNA = consonant ka
20. U+0D9B = "ඛ" = MAHAAPRAANA KAYANNA = consonant kha
21. U+0D9C = "ග" = ALPAPRAANA GAYANNA = consonant ga
22. U+0D9D = "ඝ" = MAHAAPRAANA GAYANNA = consonant gha
23. U+0D9E = "ඞ" = KANTAJA NAASIKYAYA = consonant nga
24. U+0D9F = "ඟ" = SANYAKA GAYANNA = consonant nnga
25. U+0DA0 = "ච" = ALPAPRAANA CAYANNA = consonant ca
26. U+0DA1 = "ඡ" = MAHAAPRAANA CAYANNA = consonant cha
27. U+0DA2 = "ජ" = ALPAPRAANA JAYANNA = consonant ja
28. U+0DA5 = "ඥ" = TAALUJA SANYOOGA NAAKSIKYAYA = consonant jnya
29. U+0DA3 = "ඣ" = MAHAAPRAANA JAYANNA = consonant jha
30. U+0DA4 = "ඤ" = TAALUJA NAASIKYAYA = consonant nya
31. U+0DA6 = "ඦ" = SANYAKA JAYANNA = consonant nyja
32. U+0DA7 = "ට" = ALPAPRAANA TTAYANNA = consonant tta
33. U+0DA8 = "ඨ" = MAHAAPRAANA TTAYANNA = consonant ttha
34. U+0DA9 = "ඩ" = ALPAPRAANA DDAYANNA = consonant dda
35. U+0DAA = "ඪ" = MAHAAPRAANA DDAYANNA = consonant ddha
36. U+0DAB = "ණ" = MUURDHAJA NAYANNA = consonant nna
37. U+0DAC = "ඬ" = SANYAKA DDAYANNA = consonant nndda
38. U+0DAD = "ත" = ALPAPRAANA TAYANNA = consonant ta
39. U+0DAE = "ථ" = MAHAAPRAANA TAYANNA = consonant tha
40. U+0DAF = "ද" = ALPAPRAANA DAYANNA = consonant da
41. U+0DB0 = "ධ" = MAHAAPRAANA DAYANNA = consonant dha
42. U+0DB1 = "න" = DANTAJA NAYANNA = consonant na
43. U+0DB3 = "ඳ" = SANYAKA DAYANNA = consonant nda
44. U+0DB4 = "ප" = ALPAPRAANA PAYANNA = consonant pa
45. U+0DB5 = "ඵ" = MAHAAPRAANA PAYANNA = consonant pha
46. U+0DB6 = "බ" = ALPAPRAANA BAYANNA = consonant ba
47. U+0DB7 = "භ" = MAHAAPRAANA BAYANNA = consonant bha
48. U+0DB8 = "ම" = MAYANNA = consonant ma
49. U+0DB9 = "ඹ" = AMBA BAYANNA = consonant mba
50. U+0DBA = "ය" = YAYANNA = consonant ya
51. U+0DBB = "ර" = RAYANNA = consonant ra
52. U+0DBD = "ල" = DANTAJA LAYANNA = consonant la
53. U+0DC0 = "ව" = VAYANNA = consonant va
54. U+0DC1 = "ශ" = TAALUJA SAYANNA = consonant sha
55. U+0DC2 = "ෂ" = MUURDHAJA SAYANNA = consonant ssa
56. U+0DC3 = "ස" = DANTAJA SAYANNA = consonant sa
57. U+0DC4 = "හ" = HAYANNA = consonant ha
58. U+0DC5 = "ළ" = MUURDHAJA LAYANNA = consonant lla
59. U+0DC6 = "ෆ" = FAYANNA = consonant fa

Spot the anomaly? Well, U+0DA5 "SINHALA LETTER TAALUJA SANYOOGA NAAKSIKYAYA" is out of order.

U+0DA5 from r12a

As an English speaker, the codepoint order, alphabet order and collation order of the letters "A" to "Z" are identical; so having subtle anomalies like this feels jarring. So jarring, in fact, that I checked it against three different sources (Unicode CLDR, MySQL and dictionary.gov.lk) to make sure I hadn't made a transcription error.

It's a bit like having the English alphabet "ABCDEFGHIJKLMNOPQRSTUVWXYZ" but listing words in an English dictionary in a different order, such as "ABCDEFGHIJKLPMNOQRSTUVWXYZ".

You only really need to nail down the order of letters of an writing system when you start creating reference dictionaries. However, as the Sinhala Dictionary Compilation Institute says, this didn't happen until British colonial rule of what became Sri Lanka. It's impossible to imagine that the British compilers didn't impose some of their preconceptions on the process and therefore muddied the ordering waters.

As Richard Gillam pointed out, Sinhala has a large number of letters and U+0DA5 "SINHALA LETTER TAALUJA SANYOOGA NAAKSIKYAYA" is one of those that doesn't fit into the canonical Brahmic consonant ordering utilised by ISCII.

A survey by Weerasinghe, Herath and Gamage (2006) supplies many definitions of Sinhalese "dictionary order" in current use. Indeed, even if Unicode CLDR collation is adopted as a single de facto standard, the collation tailoring metadata is considered "live", and therefore liable to change anyway.