On 12/03/2002 05:16:14 PM Antoine LECA wrote: >This issue is of relevance to the rendering engines. For example, >Microsoft's Uniscribe refuse to draw U+095x on top of any syllable >which is not Devanagari. I believe this behaviour is incorrect, >but the Script.txt file seems to assert MS position.
I don't think the Script.txt file isn't intended to imply such implementation behaviours, though it's easy to imagine some implementers might treat it that way. There is a potential concern in Uniscribe/OpenType: substitution and positioning rules in OT are organised hierarchically by script then by individual writing system / typographic groups (the label used is languages, but the intent is really groups of writing systems that share common typographic behaviours). Thus, a rule that handles positioning of a glyph for 0950 (or whatever) relative to some member of some class of glyphs must be entered somewhere under some particular script. Now, there is nothing that prohibits a font developer from creating multiple positioning rules for 0950 with different classes of base glyphs and to have a different one placed in the hierarchy under several different scripts. But there may yet be an issue on the Uniscribe side: given a string of characters, which it will begin by mapping into a string of initial glyphs, it has to decide which script tag(s) to apply to portions of the string. What I don't know is whether it generally assumes combining marks belong to a specific script, or whether it allows combining marks to inherit their script from the base characters with which they combine. At least, that's my understanding of these technologies (which comes with no guarantees). - Peter --------------------------------------------------------------------------- Peter Constable Non-Roman Script Initiative, SIL International 7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA Tel: +1 972 708 7485
