[XeTeX] Space characters and whitespace

[mskala at ansuz.sooke.bc.ca]

On Thu, 3 Mar 2011, Philip Taylor (Webmaster, Ret'd) wrote:
> if XeTeX is predicated on the use of Unicode, it should
> "understand" the semantics of Unicode code points such
> as u2009 and u202F and just do the right thing without
> having to hack things through the use of active characters.

There are really three separate questions here:

1.  Should XeTeX accept Unicode's many space characters in the input, as
opposed to just using existing TeX commands for spacing?

2.  If the answer to #1 is "yes," what exactly should be the consequences
of each space character?  Grouping this under the same question because
it's related:  to what extent should the font determine the width and
nature of each space character?

3.  If the answer to #1 is "yes," how should this be implemented - in
particular, should it be in the engine or by macros?

It sounds like you're saying "yes" to #1 and "in the engine, not in the
macros" to #3.

I note we already had some of this discussion just for the ordinary space
character (U0020) in the monospace/punctuation space thread.  To typeset
word and sentence spaces properly, XeTeX needs information that it can't
get from the font.  It seems like similar issues may arise with all the
other space characters.
-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before principles.
http://ansuz.sooke.bc.ca/