[XeTeX] XeTeX, XeTeXpicfile, and counter-intuitive behaviour

[Heiko Oberdiek]

On Thu, Dec 01, 2011 at 04:51:14PM +0100, Zdenek Wagner wrote:

> 2011/12/1 Philip TAYLOR <P.Taylor at rhul.ac.uk>:
> >
> >
> > Heiko Oberdiek wrote:
> >
> >> No, it's a whatsit. It is *not* discarded, but it isn't a box.
> >
> >
> > Right, so why isn't the \eject honoured ?
> >
> If I remember it well, whatsit is dimensionless, thus if \XeTeXpicfile
> reserves a space, it cannot be just whatsit. Anyway, discardable items
> are discarded at the break. They must not be discarded after whatsit.

Knuth has decided otherwise. Discardable items are discarded at
top of a new page unless there is a box. I have already quoted
"The TeXbook".

\write16{Hello World}
\vfil\eject
ABC
\bye

Yours sincerely
  Heiko Oberdiek