It's actually quite easy to convince Uniscribe to treat specific characters as RTL, others as LTR, and, in general, with whatever classifications you desire. Pass a preprocessed string to Uniscribe's ScriptItemize(). RichEdit has used that approach to some degree starting with RichEdit 3.0 (Windows/Office 2000). It's also a handy way to force all operators to be treated as LTR in an LTR math zone and as RTL in an RTL math zone (aside from numeric contexts for '.' and ','). And you can force IRIs to display LTR or RTL that way by classifying the delimiters such as the dots in the domain name accordingly. Some of my blog posts on http://blogs.msdn.com/b/murrays/ discuss this in greater detail.
So there's no need to change the properties of the PUA to establish PUA RTL conventions. They won't be generally interchangeable, but that's the nature of the PUA. You also have to implement such choices using rich/structured text. Plain text doesn't have a place to store the necessary properties. Most text is rich text anyway <grin>. Murray
