prerm is in libinventor1 2.1.5-10-21.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8  | #!/bin/sh
set -e
if [ "$1" = remove -o "$1" = upgrade ]; then
    temp=`mktemp /tmp/libinventor1.XXXXXX`
    rm $temp `find /usr/share/inventor/fonts -type l`
fi
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