Frequently Asked Question List for TeX

# Getting `\marginpar` on the right side

In an ideal world, marginal notes would be in “analogous” 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.

FAQ ID: Q-marginparside