apparently another thing where the course is outdated?

on my trusty 64 machine the rules are found in /lib/udev/rules.d/ while /etc/udev/rules.d/ (apart from a README) is empty.

Can it be that /lib/udev/rules.d/ are the default rules and /etc/udev/rules.d/ is meant for putting your own custom rules?

Also ... does anybody really understand the how .rules files work? When I look at them it's more like "yea, sure ... whatever"