Re: Mayan numerals

On Thu, 23 Aug 2012 23:30:49 +0100
Michael Everson <everson_at_evertype.com> wrote:

> On 23 Aug 2012, at 22:48, Jameson Quinn wrote:

> > • We will have guessed wrong on the metadata, and the
> > decision is made that a retroactive fix is the best solution, given
> > that it (say) impacts only documents which mix Mongolian with Mayan
> > numerals.

> I don't know what you think a "retroactive fix" is but it is unlikely
> that any "informative" as opposed to "normative" fix would be
> possible.

The immutable properties are:
(i) name
(ii) aliases (more can be added, but they cannot be removed)
(iii) decomposition mapping
(iv) canonical combining class
(v) case folding
(vi) case pairing (i.e. pairs and non-pairs of assigend characters
remain such).

Only (i) and (iv) seem plausible causes of problems. A canonical
combining class of zero seems to be the preferred option for script
encoding nowadays.

Combining rules may have to be extended - that might be counted as an
informative fix.

> > • We will have guessed wrong on the metadata, but anyway
> > need to encode multiple versions of the number glyphs, so having
> > used up 20 codepoints for modern users of the Mayan numerals is no
> > big loss.

> We are not supposed to encode duplicate characters.

We do where the properties necessitate, e.g. U+0241 LATIN CAPITAL LETTER
GLOTTAL STOP and U+0294 LATIN LETTER GLOTTAL STOP, or the NEW TAI LUE
and TAI THAM scripts. We also have the principal of the separation of
scripts.

Richard.
Received on Sun Aug 26 2012 - 18:29:14 CDT