Hello people. This is just of academic interest, since the fact is that a full series of subjoined characters *have* been encoded and *are* being used for Tibetan, and nothing is going to change that, but it could have an effect on future proposals for Tibetan-like scripts, so I think it is important for this matter to be discussed.
The standard says that "there were two main reasons for this choice" of choosing to encode separate subjoined characters for Tibetan rather than using an Indic-like virama model: The *second* reason provided is that due to the prevalence of stacking in Tibetan, encoding subjoined characters would cause decreased storage requirements. Well that's true for any South Indic script -- Telugu, Kannada, Grantha -- which also regularly uses stacks for representing clusters, so this is not something that is unique to Tibetan. The *first* reason stated is that "the virama is not normally used in the Tibetan writing system to create letter combinations". But this sentence conflates two things, the visible device of a vowel-killer virama as part of the attested orthography, and the abstract encoded character as part of digital text. Clearly the "is not normally used" can refer only to the former, not the latter. OK fine, so in practice the virama *with a visible form* is never used in writing Tibetan. But even for Devanagari, if it were not for Sanskrit, a visible virama is almost never used for Hindi, the prevalent language, and it is only that Devanagari is also heavily used for Sanskrit and the thing about maintaining uniformity with other Indic scripts that the visible function and the joining function were united in a single character. So it's not a big deal to separate the two functions, as is done in Khmer etc. Hypothetically even in mainland Indic we could have separate joiner-virama vs visible-virama characters. So my point is that even though the visible virama is not used in Tibetan (probably because the TSHEG separates syllables making the final consonant vowelless) one could very well have gone the Khmer way and made a separate character for that (as indeed has been done) but still have had a single joiner for causing the stacks. Or was the Khmer model of an invisible joiner a *later* bright idea? But really that doesn't hold water (I mean the "later" part) because the Indic virama model already existed, and whether or not Tibetan used the visible virama heavily need not have prevented from a virama character, which would have a visible form in appropriate contexts, causing stacking in other contexts. And even that thing about the contrast between the full-form subjoined consonants YA RA VA and half-form ones (I mean the -tags forms) need not prevent this, because you could encode a virama and have the *regular* (-tags) forms produced by it, and use separately encoded subjoined characters for the aberrant forms alone. As for the RA-MGO thing, I still am not sure how it is advisable to have a 0F6A glyphically identical to 0F62 and even if a default-ignorable ZWNJ would not have been satisfactory, some specialized non-default-ignorable conjoining-form-prevention character could be defined, which would then also be used for subjoined full-form YA RA VA avoiding those extra characters too. Or have it as you wish and encode 0F6A and 0FBA-0FBC to avoid such specialized character stuff, but still for the rest of the consonants including the prevalent -tags forms of YA RA VA, the justification provided for a full series of atomic subjoining characters seems quite insufficient... -- Shriramana Sharma ஶ்ரீரமணஶர்மா श्रीरमणशर्मा
