L2/01-079 From: Peter_Constable@sil.org Sent: Monday, January 22, 2001 1:07 PM Subject: Re: PDUTR #27: Unicode 3.1 Some further comments (more substantive than editorial): - Article 5, section 13.2: In the third paragraph: "To allow for finer control over ligature formation, in Unicode 3.0.1 the definitions... have been broadened... " This wording makes it sound like 3.0.1 is a typo (since it's clear that the text is appearing in version 3.1). Suggested change: "...the definitions... were broadened..." More substantively, this section addresses particular issues in relation to Arabic, but does not at all mention how the broadened semantics relate to Indic scripts like Devanagari. Note that for Devanagari ZWJ behaves somewhat opposite to the behaviour suggested by this section: C + virama + ZWJ + C results in a half form of the first consonant rather than a full ligature, while C + virama + C (the same thing without ZWJ) results in a full ligature. If Indic shaping were consistent with the behaviour described in this section, then arguably the opposite should happen. It seems to me that this at least needs some brief explanation. Toward the end of this section, some suggestions for font developers are provided, namely for ligature mappings to be extended to allow for ZWJ to occur; e.g. < f, i > ==> gLig_fi or < f, ZWJ, i > ==> gLig_fi. Following this, the last paragraph of the section begins, "Current Arabic shaping algorithms should need no change; optional liguatures just would not be promoted by ZWJ, but current text should not be affected." Indeed, current text won't be affected in existing implementations, but it seems to me that there's potential for future text not to work with existing implementations. E.g. I would guess that < lam, ZWJ, alef > would likely not result in a ligature in at least some existing implementations, but in cursively connected forms. This is what appears to occur in current builds of Uniscribe, for example. This text appears to at least be misleading. - Peter --------------------------------------------------------------------------- Peter Constable Non-Roman Script Initiative, SIL International 7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA Tel: +1 972 708 7485 E-mail: