[XeTeX] Getting completely the wrong glyphs when using characters from Latin Extended B

[Philip TAYLOR]

Akira Kakuto wrote:

> Please try
> \setmainfont{Lucida Sans Unicode}
> without quotation, when you use fontspec.

Khaled Hosny wrote:

 > You don't need the quotes here, fontspec already add them, I guess the
 > actual font definition will be now something like
 > \font\whatever=""Lucida Sans Unicode""

Thanks Akira & Khaled, but now I am confused again ...

In an earlier thread (see below), Joanthan Kew said
that string quotes were necessary if one was trying
to reference a TTF/OTF/Type-1 font rather than a
TFM-based (TeX) font.  How, then, does \setmainfont
know whether I want a TTF/OTF/Type-1 font rather than a
TFM-based (TeX) font if I am not permitted to use quotation
marks to indicate that I want the former ?

** Phil.
--------
> Use quote marks:  \font defaultfont = "Optima" at 20pt
>
> XeTeX supports both TFM-based files and "native" TrueType/OpenType/Type1 fonts on the platform. It should try both, if necessary, before finally giving up; but in the case where it tries TFM first, the result (if you have mktextfm, etc., enabled) can be a lot of unpleasant messages as those subsidiary tools fail. But if you quote the font name, it takes this as a hint to try for a platform font first.
>
> So "best practice" is to ALWAYS quote font names, except when you really mean to use a traditional TFM file.
>
> JK