[XeTeX] Long dash "--" in Latex

[Jonathan Kew]

On 1 Jul 2004, at 5:01 pm, ชนพ ศิลปอนันต์ wrote:

> -- and --- are ligatures; they are converted to en-dash and em-dash
> respectively by ligature rules in traditional TeX's way. Therefore, 
> they
> are not available in XeTeX.

Right; or, to be more specific, they're handled by ligature rules in 
the TFM files of the Computer Modern fonts (and many other fonts for 
which TFMs have been created). They'll work just the same in XeTeX *if* 
you're using such fonts.

But if you're using AAT or OpenType fonts *without* TFM files--the 
capability which is the major "selling point" of XeTeX--then access to 
any ligatures is dependent on ligature rules encoded in the AAT or OT 
tables of the font you're using. And -- and --- are not normally 
implemented there.

On the other hand, you can simply use the Unicode en-dash and em-dash 
characters directly in your source text.

Jonathan