The smali files (if I understand correctly) are the result of
decompiling dex files, and part of the output of apktool.

https://github.com/JesusFreke/smali
https://ibotpeaches.github.io/Apktool/

The format is plain text, and the first two lines start with ".class "
and ". super" respectively. This is often followed by ".source " but not
always.

    Christoph
