- From: Phillips, Addison <addison@lab126.com>
- Date: Thu, 19 Jun 2014 19:44:27 +0000
- To: Asmus Freytag <asmusf@ix.netcom.com>, Najib Tounsi <ntounsi@emi.ac.ma>, Matitiahu Allouche <matitiahu.allouche@gmail.com>, "www-international@w3.org" <www-international@w3.org>
> > On 6/19/2014 11:27 AM, Najib Tounsi wrote: > > On 6/19/14 2:51 PM, Matitiahu Allouche wrote: > >> > >> 11) In 2.2 table of Compatibility Equivalence, the third example is > >> labelled "Cursive forms". I think that this would be better labelled > >> "character shapes". Rationale: the example shows various shapes of an > >> Arabic letter. But similar examples could be taken from final versus > >> non-final shapes of some Hebrew letters, or from the final versus > >> non-final shapes of the Greek sigma letter. Hebrew and Greek are not > >> cursive scripts, so the issue here is having position-dependent > >> shapes, not cursiveness. > > The Greek final sigma uses a different character code which is not a > compatibility equivalent. > > The reason is that, unlike Arabic positional shaping, the selection of the final > form cannot be determined algorithmically at rendering time and would > otherwise introduce the need to use ZWNJ with Greek; not a good tradeoff. > > Whatever example is used needs to be limited to cases of automatic shape > selection at rendering. > Context matters here. The table is not merely one containing characters that use contextual shaping. These are *specifically* characters with compatibility decompositions in Unicode and the table is illustrating the various kinds of compatibility decomposition. I tend to agree with Mati's comment that "cursive forms" is not that accurate a label. In practice only Arabic uses <initial>, <medial>, <final>, and <isolated> decompositions, though, so the other offered examples are not what the table is meant to illustrate. The items in the table are the four compatibility variations of ARABIC LETTER NOON (U+0646). Note that this table is identical to Figure 2 in UAX#15. Addison
Received on Thursday, 19 June 2014 19:44:58 UTC