depthcharge was: Ignoring pdftex primitives

[Chris Rowley]

I wrote --
> Taco wrote --
> > > 
> > > "widthcharge.png" needs only 1 \noexpand, "heightcharge.png" needs 2
> > > (but more \noexpands don't do any harm). "./heightcharge.png" needs
> > > none, of course, but that's not portable across filesystems.
> 
> Aagh!  I wish you had not told me that:-) ... now I need to completly
> reconstruct my personal model of how that bit of TeX works

I'm OK again now with this one ... when it does find a
<rule dimension>, it starts scanning for width again,
etc, etc, ad infinitum ... what a lot of scanning!
This is all as per the syntax on p282.

Whilst we are in tutorial mode, another difference between rule specs
and glue specs is: with glue, when both are present, the plus and
minus bits must come in that order; this feature caught me a few
times!


chris