I would surely agree with the what Ken says on that topic. I do think myself
that for a variety of reasons (start with backwards compatibility issues..)
the proposed unification for the greek sigma is not a good idea.
History shows that the alluded rule for the final sigma (Tim Partridge) although correct it has no chance of being correctly processed by any future
code. Unification will create a lot of problems. Therefore I don't agree on
such modification as well.
> Tim Partridge commented:
> > In message <9711281918.AA03595@unicode.org> Doug Ewell recently said:
> > > As I read this, I keep thinking about U+03C2 GREEK SMALL LETTER FINAL
> > > SIGMA and U+03C3 GREEK SMALL LETTER SIGMA. If I am not mistaken,
> > > these are indeed just presentation variants, and there is indeed a
> > > straightforward rule (end-of-word) to determine which glyph should be
> > > displayed. So, strictly speaking, this principle would seem to point
> > > to the unification of U+03C2 and U+03C3 (and several similar pairs in
> > > the Hebrew block, for that matter).
> > There is a straight forward rule for Greek, as you state. But applying
> > this as a default could cause problems when Greek letters are used
> > in mathematics. Sigma is used in statistics to represent standard
> > deviation. I'm surprised Unicode doesn't have a separate code point
> > for this considering its obsession with U+2126 micro sign, U+00B5 ohm sign,
> > U+2135 alef symbol (Hebrew, not Greek) etc. Perhaps it's because the others
> > are designators / constants rather than variables.
> It doesn't have anything to do with their mathematical function, but
> rather with the source encoded character sets that were in consideration
> when the original collection of characters was pulled together.
> U+00B5 MICRO SIGN is in ISO/IEC 8859-1 ("Latin-1"), and in the preexisting
> ISO nomenclature was distinguished from U+03BC GREEK SMALL LETTER MU. There
> was no choice but to provide for separate encoding in Unicode.
> The encoding for Greek Sigma is dependent on the preexisting encoding of
> ISO/IEC 8859-7, as well as the Greek encodings that standard is derivative
> U+2126 OHM SIGN and U+2135 ALEF SYMBOL, and other letterlike symbols that
> ended up with separate encodings also had preexisting separate treatments
> in at least one source encoded character set.
> The implication that Unicode has an obsession for making such distinctions
> on their functional status is incorrect. If anything, a careful reading
> of UnicodeData-2.0.14.txt, available on the website, will demonstrate that
> the letterlike symbols which otherwise appear to be identical to existing
> letters in an encoded alphabet are all given canonical equivalences to
> those other letters. This is the UTC's way of dealing with the fact that
> we have to live with the dual encodings, for compatibility with other
> encoded character sets, while realizing that cloning such characters based
> on mathematical (or other) function is not a good idea.
> --Ken Whistler
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