Definition Question

Based on an offhand comment the other day, I'd love to hear from my wise and worldly (academic) readers to solve a definition question. (Wise and worldly non-academic readers, please indulge a little 'inside baseball' for today.)

How does your college or university define a credit hour? Put differently, if you propose a new course, what determines how many credit hours it gets? Does a given number of credits require a given amount of 'seat time'? If it does, what happens with online classes?

I'm particularly interested in how it defines credit hours for nontraditional formats, online delivery, etc.