Guide to LaTeX (4th Edition) (Tools and Techniques

C.6. Search for subtle errors 435
badness 5504 is T E X’s estimate of how unacceptable the spacing is: the smaller
this number the better.
Underfull \vbox ....
The page has been broken with head and foot justified, but T E X judges
the amount of inter-paragraph spacing to be possibly unacceptable. The
badness number here corresponds to the quantity with the same name
from the Underfull \hbox warning.
C.6 Search for subtle errors
At some point or another you will encounter an error message for which
you cannot identify any cause, try as you may. For such devious errors,
we recommend the following search strategy:
1. Copy the file twice into a previous and a working copy (in addition
to the original, which remains untouched during this search).
2. In the working copy, find the outermost environment where the error
occurred and remove one or more inner environments. If there are
no inner environments, shorten the remaining text. Process the file
with L AT E X once more.
3. If the error still occurs, copy the shortened working copy to the
previous copy and repeat step 2. If the outer environment in step
2 is \begin{document} ... \end{document}, the shortening may
be carried out by simply inserting \end{document} at some earlier
point.
4. If the error is no longer in the shortened working copy, copy the
previous copy back to the working copy. The error is still present in
this version. Remove less of the text than last time and repeat steps
2 to 4.
5. If the error is found to be in the next innermost environment, repeat
the procedure for this environment with steps 2 to 4.
With this strategy, the error may be localized to one command or to the
innermost environment with only a small remaining structure. If the
error still cannot be identified in spite of its being precisely localized,
seek help from a more experienced colleague or from the computing
center. However, it is normally possible to recognize the mistake once the
position of the error has been found.
It does happen that even though the error has been corrected, the same
error message appears on the next L AT E X process run. This is because of
the internal transfer in information through the L AT E X auxiliary files, which