### “Too deeply nested”

This error appears when you start a LaTeX list.

LaTeX keeps track of the nesting of one list inside another. There is a set of list formatting parameters built-in for application to each of the list nesting levels; the parameters determine indentation, item separation, and so on. The `list` environment (the basis for list environments like `itemize` and `enumerate`) “knows” there are only 6 of these sets.

There are also different label definitions for the `enumerate` and `itemize` environments at their own private levels of nesting. Consider this example:

>     \begin{enumerate}
>     \item first item of first enumerate
>       \begin{itemize}
>       \item first item of first itemize
>         \begin{enumerate}
>         \item first item of second enumerate
>         ...
>         \end{enumerate}
>       ...
>       \end{itemize}
>     ...
>     \end{enumerate}

In the example,

- the first `enumerate` has labels as for a first-level `enumerate`, and is indented as for a first-level list;
- the first `itemize` has labels as for a first level `itemize`, and is indented as for a second-level list; and
- the second `enumerate` has labels as for a second-level `enumerate`, and is indented as for a third-level list.

Now, as well as LaTeX knowing that there are 6 sets of parameters for indentation, it also knows that there are only 4 types of labels each, for the environments `enumerate` and `itemize` (this “knowledge” spells out a requirement for class writers, since the class supplies the sets of parameters).

From the above, we can deduce that there are several ways we can run out of space: we can have 6 lists (of any sort) nested, and try to start a new one; we can have 4 `enumerate` environments somewhere among the set of nested lists, and try to add another one; and we can have 4 `itemize` environments somewhere among the set of nested lists, and try to add another one.

What can be done about the problem? Not much, short of rewriting LaTeX — you really need to rewrite your document in a slightly less labyrinthine way.

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