Right now, `@part` in the ToC is typeset with an empty box for the
sectioning number. This doesn't look correctly formatted if there are
more than 9 chapters, see the attached image.
Since `@part` is outside of the sectioning hierarchy I suggest to not
indent it at all, see the second attached image; doing so has the
additional bonus that it sticks out more prominently – right now,
because it uses the same font and size as ToC entries for `@chapter`,
it can be easily missed. I could even imagine to use a slightly
increased font size for the ToC entry.
I used the following code.
```
@tex
\gdef\partentry#1#2#3#4{%
\vskip 0pt plus 5\baselineskip
\penalty-300
\vskip 0pt plus -5\baselineskip
\vskip 1\baselineskip plus .33\baselineskip minus .25\baselineskip
\begingroup
\chapentryfonts
\extrasecnoskip=0.4em
\entryinternal{#1}{}%
\endgroup
\nobreak
\vskip .25\baselineskip plus .1\baselineskip}
@end tex
```
Werner
