Files should be named xx-descriptive-name.rules, the xx should be
chosen first according to the following sequence points:
< 60 most user rules; if you want to prevent an assignment being
overriden by default rules, use the := operator.
these cannot access persistent information such as that from
vol_id
< 70 rules that run helpers such as vol_id to populate the udev db
< 90 rules that run other programs (often using information in the
udev db)
>=90 rules that should run last
