> Date: Fri, 23 Oct 2015 23:16:32 +0100 > From: Richard Wordingham <[email protected]> > > "C6: A process shall not assume that the interpretations of two > canonical-equivalent character sequences are distinct." > > Firstly, I have grave difficulties assigning mental activities to > processes. > > Secondly, it may be possible to interpet "A process shall not assume X" > as "A process shall function correctly regardless of whether X holds." > > However, let image(Y) be the bitmap depicting the string Y. Then the > following logic would be non-compliant: > > if A and B are canonically equivalent and image(A) and image(B) are > different, then > write(A, " and ", B, "are canonically equivalent but have different > images ", image(A), " and ", image(B)); > end if > > The logic is non-compliant, for if it is invoked then the write > statement will only work correctly if image(A) and image(B) are > different, i.e. if A and B are interpreted differently. Apparently it > is permissible to render canonically equivalent sequences differently, so > image(A) and image(B) might be different even though canonically > equivalent. > > I therefore conclude that C6 is in some language that I do not > adequately understand.
AFAIU, Unicode is about processing text, and only mentions display rarely, where it's directly related to the processing part. So the above is about _processing_ canonically-equivalent sequences, not about their display. When looked at in this way, I see no difficulties in understanding the text. > > Again, I do know nothing about Thai, but if in TUS an abugida can be > > addressed to as an alphabet if the same is used as such, it seems to > > me that the word 'alphabet' has a pretty extended meaning in TUS. > > TUS tries to make accurate use of the distinction between 'alphabet', > 'abugida' and 'abjad', 20th century jargon promoted if not invented by > Peter Daniels. The distinction lies in the way vowels are indicated - > always / with a default / not at all. The distinction may be useful > for a writing system, i.e. a way of using the 'script', but it rapidly > encounters the problem that a script may have several different writing > systems. For example, the presence or absence of vowel marks switches > the Arabic and Hebrew scripts, as used for those languages, between > being an abjad and being an alphabet. The Hebrew script is never an alphabet, AFAIU, it's likely an abugida when the vowel marks are used. The so-called "full spelling", where some vowels are indicated by consonants, does not replace all the vowels with consonants, so it isn't, strictly speaking, an alphabet in the above sense.
