[tex4ht] imakeidx Umlaut problems in tex4ht

["Jürgen Hubert"]

Hello everyone,

as I am close to finalizing my massive ebook manuscript (102K words so far), I have encountered another strange issue - apparently imakeidx doesn't sort index entries properly when they start with an Umlaut. Here is some minimal code:

----------------

\documentclass[oneside]{scrbook}

\ifdefined\HCode
\usepackage[noautomatic]{imakeidx}
\else
\usepackage[]{imakeidx}
\fi
\usepackage[hyperindex=true]{hyperref}

\makeindex[intoc=true,name=place,title=Places]

\begin{document}

\chapter{Testchapter}

Alterlingen\index[place]{Alterlingen}

Älterlingen\index[place]{Älterlingen}

Oberlingen\index[place]{Oberlingen}

Öberlingen\index[place]{Öberlingen}

Überlingen\index[place]{Überlingen}

Unterlingen\index[place]{Unterlingen}

\printindex[place]

\end{document}

------------------

When I compile this with pdflatex, I get the following index:

Alterlingen, 1

Oberlingen, 1

Unterlingen, 1

Älterlingen, 1
Öberlingen, 1
Überlingen, 1

Basically, the Umlaut index entries are listed at the very end of the index. Which is not quite technically correct, but close enough for an English-language publication ("let's put all those weird, foreign characters into their own corner!").

However, when I compile this code with tex4ebook, I get:

A

Alterlingen, 1

O

Oberlingen, 3
Öberlingen, 4
Älterlingen, 2
Überlingen, 5

U

Unterlingen, 6


In other words, _all_ index entries that start with an Umlaut are listed under "O" for some reason - which clearly shouldn't be the case.

Cheers,

- Jürgen