Frequently Asked Question List for TeX

Other things being equal, TeX will aim to position subscripts and superscripts in places that “look good”. Unfortunately, it only does this for the sub- and superscripts of each atom at a time, so if you have

```
$ X^{1}_{2} X_{2} $
```

the second subscript will appear higher, since the first has moved down to avoid the superscript; the effect can be noticeably distracting:

You can avoid the problem, for a single instance, by

```
$ X^{1}_{2} X^{}_{2} $
```

here, the dummy superscript has the requisite “pushing down” effect:

While this technique does what is necessary, it is tedious and
potentially error-prone. So, for more than one or two equations
in a document, the LaTeX user is advised to use the
`subdepth`

package, which forces
the lower position for all subscripts.

FAQ ID: Q-subheight

Tags: *math*