I've been setting up case rules and escalation rules, but I don't see anything that would allow me to create a date-based rule that is relative, for example:

-- number of days before today
-- number of days after the case creation date
-- number of days since the last modified date

It appears that you can only do this based on hours, not number of days.  Where dates are available, you have to pick actual dates.  Do I understand this correctly? Or did I miss something and there really is a way to do it?

Thanks,
Cecelia