There are two variants of the Bopomofo Extensions glyphs used for local languages, like Minnan and Hakka.
According to Unicode [[!img http://debian.linux.org.tw/pub/3Anoppix/people/arne/unicode32.png]
According to Mr. Yang Qing-Chu (楊青矗), used in modern teaching materials for Hakka and Minnan instead of the original Bopomofo Extensions. These are called MBE. [[!img http://debian.linux.org.tw/pub/3Anoppix/people/arne/unimbe.png]
The font package contains both variants. The original font uses stylistic alternatives as defined in the OTF standard. If your application cannot support this, you can patch the font using the provided xdelta file to create a MBE version. You can then install both fonts in parallel.