[XeTeX] Proper way to set up OT Features

[Will Robertson]

On 2011-02-12 11:58:07 +1030, David Perry 
<hospes.primus at verizon.net> said:

> In one of my fonts, I'm having a hard time getting the OT features to
> work correctly in XeLaTeX.
> 
> If I include the following line:
> 	\setmainfont[Numbers=Lowercase,Ligatures={Rare,Historical}]{Cardo}
> 
> then the oldstyle numerals and ligatures work fine.  If I omit the
> options from the \setmainfont command and add the features in the body
> of the document using the normal \addfontfeature{ } or \addfontfeatures{
> }, the features don't work (but there are no error messages during
> compilation).

Hmmm, is this a bug in fontspec? I can't think of an alternative 
explanation. Can you try it out with a different font?

> Also, I cannot turn off the standard ligatures with the
> Ligatures=NoCommon command.

I think this is a font problem; this option corresponds to the OpenType 
"liga" feature.

But I don't have much experience with creating OT features in a font; I 
hope others here can provide more info...

Will