[rules-users] Time Units Support - execution and repeating period

Hi, I want to realize a rulebased condition-monitoring. Rules should fire only once a week, if a condition still is true. But they should processed once per hour. So, first I have to realize a exceution period (e.g. once per week) and a test/repeating period to check new conditions. I just read something about time units support and timer nodes, but do not find more detailled manuals. Are addtional features in drools available, to support this requirement? Where I can find more information, examples about time unit support? Thanks a lot. Thorsten Trägenap