[XeTeX] xdv specification

[Jonathan Kew]

On 10 May 2006, at 7:47 pm, Geoffrey Alan Washburn wrote:

> 	Is there a document somewhere that describes the xdv file format?
> Something like Part 31 of the TeXBook perhaps.  Thanks!

Not as such, but you can look at the source code; see <http:// 
scripts.sil.org/svn-view/xetex/TRUNK/TeX/texk/web2c/xetexdir/xetex- 
new.ch> and look for the section "[31] Device-independent file  
format". Of course, any comments found there are less authoritative  
than the actual code.... ;-)

You can also look at the code in xdv2pdf and/or xdvipdfmx that reads  
the .xdv output. In xdvipdfmx, you'd want to look at <http:// 
scripts.sil.org/svn-view/xdvipdfmx/TRUNK/src/dvi.c>, and in  
particular the sections added within "#ifdef XETEX" conditionals.

BTW, I have not necessarily "frozen" the .xdv format yet--note the  
"pre-release" version numbers on everything! XeTeX only adds a  
handful of new op-codes to the .dvi format, but the additions have  
been revised several times over the past couple of years, as xetex  
and the output drivers have evolved. After "version 1.0" of XeTeX is  
out, I'll feel more obligated to maintain compatibility, but for now  
it's a (potentially) moving target. For example, there have been  
requests to allow XeTeX to use fonts that are not "installed" in the  
host OS, and if this is implemented, it will involve an extension to  
the (already-extended) form of font definition that is used in  
the .xdv output.

JK