I am using xindy for my index but I get this here:
Does anyone know why a single letter (group heading) remains on the bottom of a column? How to force it into the next column?
It will be hard to create a MWE since the only command used is: \printindex... However here is some of the contents of the *.ind file:
\begin{theindex}
\providecommand*\lettergroupDefault[1]{}
\providecommand*\lettergroup[1]{%
\par\textbf{#1}\par
\nopagebreak
}
\lettergroup{A}
\item \vn ạ, 114
\item \vn ai, 19, 42
\subitem ai chẳng, 39
\subitem ai cũng, 38
\indexspace
\lettergroup{Â}
\item \vn âm, 33
...
\item \vn ơi, 76
\indexspace
\lettergroup{P}
\item \vn phải, 2, 45, 84, 120
\subitem phải không, 3
\item \vn phảy, 33
\item \vn phần, 32
\indexspace
\lettergroup{Q}
...
\item \vn xong, 43
\end{theindex}

*.indfile to the question. Is there some way to not only avoid a page break (as\nopagebreakdoes) but also a column break? – Dominik Nov 10 '15 at 07:06