[This question about `{(x+y)}^2` vs `(x+y)^2`](https://tex.stackexchange.com/q/104004/14996) drew my attention to the slightly different vertical positioning of super- and subscripts for such expressions. Compare `(x+y)^8_8` (left) and `{(x+y)}^8_8` (right) [all expressions in math mode]:

![different vertical positioning of super- and subscripts](https://i.stack.imgur.com/AU9Pk.png)

```
\documentclass{article}
\begin{document} \((x+y)^8_8\), \({(x+y)}^8_8\) \end{document}

```

(This minimal example code is barely worth posting.)

This raises some questions for me:

* Why is the vertical positioning different in the two expressions?
* Is there anything the LaTeX user should pay attention to to get such vertical positioning "right" (this is assuming that there is deeper rationale behind the difference)?
* Is there an easy way of getting such expressions to always have identical positioning of super- and subscripts?

The answers to the linked question above advise against the version with `{ }`, so I assume that any rationale for the difference in vertical positioning will require a different example term.