Well, it's not that complicated. Ligatures in German must not happen
at compound break points, while they can be applied to ordinary break
points.
Consider the word `Dorfladen' (village shop). Using `=' to indicate a
compound break point and `-' for normal ones, the proper break points
are `Dorf=la-den' which means no `fl' ligature. Note that `Fladen'
means `cow dung', so having a ligature there is really bad.
But "Dorfladen" is not ambiguous. Asmus war referring to ambiguous cases
created by the way compound words are spelled in German. For those, some
user interaction is necessary, and it's my view that there are
unobtrusive ways of interacting with the user about this.
(But then it needs to be acknowledged that ambiguous cases probably
exist or can be constructed in a lot of languages. And the frequency of
such ambiguity occurring in actual German text isn't that high. Even
more so if one takes into account the orthographic recommendation to use
an explicit hyphen in ambiguous cases. But of course these cases, if
they occur, need to be handled nevertheless.)
Stephan
