[EXT] Re: l3backend: adding new DVI specials?

[Philip Taylor]

Zdenek Wagner wrote:

> Yes, but as was already mentioned, pdftex can distinguish between a
> PDF mode and a DVI mode but cannot guess the DVI driver. The
> regression test must follow specification and select the DVI driver
> used further in the test. I am afraid there is no other possibility.
> XeTeX invokes xdvipdfmx explicitly so it can know which driver is
> used, it is not the case of pdftex in the DVI mode.

It seems to me (as an outsider to this discussion) that the best 
solution — as opposed to the simplest — would be to define a universal 
\special which all drivers would be required to "understand", and thus 
not generate a warning.  The data within this special could then use 
(for example) keyword:value pairs to pass different information — or 
none at all — to different drivers.

Philip Taylor