[latexrefman] calc package

[Karl Berry]

    * shouldn't we use @dmn{¦} for units

It's not a requirement (all it does is insert a thinspace).
I prefer not to, to keep the source smaller/simpler.

    * narrow -> narrower ? (Not being a native English speaker¦)

Correct.

    * missing @PkgIndex{calc}

Agreed.

    * \dimexpr can be used with modern engines

Ok, but that's a big can of worms to be opening. I'm not sure if LaTeX
explicitly supports \dimexpr and other eTeX primitives at the user
level, even though they require etex (and more) for building the formats now. 

The whole question of arithmetic, not to mention other e-primitives, is
something to be explored in other nodes. That would/will be a big job.

But for purposes of \includegraphics, I guess it's true enough that the
example could be changed to merely use \dimexpr nowadays. If it actually
works, which I wouldn't assume without testing. --thanks, karl.