Ligatures, which are a pleasing feature of TeX's use of fonts, should not be placed in German words between the word stem and the rest of the word.

The rmligs package is a perl script that takes input in ISO 8859-1 or -15, UTF-8 or LaTeX-style umlaut encodings ("a, "u, etc.), and inserts a break where an inappropriate ligature would appear. So, for example, ‘Auflage’ will be changed to ‘Auf"|lage’, which typesets in a typographically correct fashion.

The author is Björn Jacke. The package is Copyright © 1999-2002 Björn Jacke.