Status of Thai Angkhandiao

[Richard Wordingham]

Thai has two identical or very similar punctuation-like characters,
'paiyan noi' (ไปยาลน้อย), definitely encoded as ฯ U+0E2F THAI CHARACTER
PAIYANNOI, and 'angkhan diao' (often transliterated 'angkhandeaw')
(อังคั่นเดียว).  Paiyan noi is an abbreviation mark, historically the
same in name as ៘ U+17D8 KHMER SIGN BEYYAL, which however corresponds in
form and meaning to the Thai sequence 'paiyan yai' - ฯลฯ.  Angkhandiao
is historically a single danda, contrasting with the double danda
U+0E5A THAI CHARACTER ANGKHANKHU.  (They are both very little used in
modern Thai.)

One piece of evidence that paiyannoi and angkhandiao are two separate
characters is that ISO 11940 uses different glyphs for them and
prescribes different transliterations for them:

ǀ U+01C0 LATIN LETTER DENTAL CLICK for angkhandiao
ǁ U+01C1 LATIN LETTER LATERAL CLICK for U+0E5A THAI CHARACTER ANGKHANKHU
ǂ U+01C2 LATIN LETTER ALVEOLAR CLICK for U+0E2F THAI CHARACTER PAIYANNOI

(I would have said that U+0964 DEVANAGARI DANDA and U+0965 DEVANAGARI
DOUBLE DANDA would have been better for the first two, but these are
declared (Script_Extensions property) not to be used as part of the
Latin script, though I thought they were used for Sanskrit.)

Has Unicode ever ruled on whether U+0E2F includes angkhandiao?

Richard.