At 22:57 5/12/2002, Amir Herman wrote: >If this is the case, why in Unicode it have Arabic Presentation A & C to >present the final, medial, and initial form of Arabic characters?
Ah, this is an historical oddity. Character inclusion in Unicode is governed by a number of principles, which are not necessarily mutually inclusive. So the 'purity' of the character encoding model is sometimes sacrificed in the interests of another principle, such as the need to provide ono-to-one backwards compatibility mappings with older character sets. So Unicode effectively inherits some of the poor design or technical limitations of pre-existing character sets. I'm sure Ken Whistler or one of the other UTC members can explain exactly why the Arabic presentation forms ended up being encoded. I seem to recall that there was some political pressure (from Egypt?) that resulted in the unfortunate encoding of an arbitrary subset of potential ligature forms, but I don't know the details or whether this pressure was also responsible for the inclusion of the final, medial and initial forms. Some existing software, e.g. Adobe PageMaker and InDesign ME (made by WinSoft in France), makes use of the presentation form encodings to enable a very basic kind of Arabic shaping. Developers of such software to whom I have spoken seem to be aware that this is a bit of a hack, and that a more sophisticated and elegant Arabic shaping methodology requires only the codepoints in the basic Arabic block. Everything else can be handled at the glyph processing stage. John Hudson Tiro Typeworks www.tiro.com Vancouver, BC [EMAIL PROTECTED] Last words of Jesuit grammarian Dominique Bouhours: "I am about to — or I am going to — die; either expression is used."
