### Getting `\``marginpar` on the right side

In an ideal world, marginal notes would be in “analagous” places on every page: notes on an even-side page would be in the left margin, while those on an odd-side page would be in the right margin. A moment’s thought shows that a marginal note on the left needs to be typeset differently from a marginal note on the right. The LaTeX `\``marginpar` command therefore takes two arguments in a `twoside` documents: `\``marginpar[`left text`]{`right text`}`. LaTeX uses the “obvious” test to get the `\``marginpar`s in the correct margin, but a booby-trap arises because TeX runs its page maker asynchronously. If a `\``marginpar` is processed while page n is being built, but doesn’t get used until page n+1, then the `\``marginpar` will turn up on the wrong side of the page. This is an instance of a general problem: see “finding if you’re on an odd or an even page”.

The solution to the problem is for LaTeX to ‘remember’ which side of the page each `\``marginpar` should be on. The mparhack package does this, using label-like marks stored in the `.aux` file; the memoir class does likewise.

`memoir.cls`
  macros/latex/contrib/memoir (gzipped tar, browse)
`mparhack.sty`
  macros/latex/contrib/mparhack (gzipped tar, browse)

This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=marginparside