Negative page numbers

[Dan Eble]

> Real
> Page_breaking::page_height (int page_num, bool last) const
> {
>   // The caches allow us to store the page heights for any
>   // non-negative page numbers.  We use a negative value in the
>   // cache to signal that that position has not yet been initialized.
>   // This means that we won't cache properly if page_num is negative or
>   // if calc_height returns a negative number.  But that's likely to
>   // be rare, so it shouldn't affect performance.

This comment seems to imply that there are legitimate uses for negative page 
numbers.  Is anyone willing to agree that I am interpreting it correctly?

Thanks,
— 
Dan