Thanks to you all for the marvelous help you have given me on how to use bidi with plain xetex. It's obvious to me now that I will have to upgrade my 2009 version of TeX Live. I don't know why Ubuntu still makes available only this old version and not the latest version. Fortunately John Was's suggestions have worked out very well with my old version of TeX Live and I can now make an Arabic file using xetex.
Nicholas -------------------------------------------------- Subscriptions, Archive, and List information, etc.: http://tug.org/mailman/listinfo/xetex
