/usr/lib/aspell/bg.dat is in aspell-bg 4.1-3ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 | # Bulgarian data file
name bg
charset cp1251
soundslike bg
keyboard bulgarian
affix bg
affix-compress true
special ' -*-
|