[Koha] Koha and fees

[Tim Young]

Hi,
I am helping some people set up Koha.  I am not very familiar with 
it, and I thought a quick email might save me a lot of head-scratching...

We have a bunch of research books which are set up to be of type 
"short-term loan".  We have a rule where they are checked out for 2 
hours, and start to get fined for every hour after those two hours.

At the end of the day, however, we are OK with students checking 
these books out overnight and returning them first thing in the 
morning.  The problem is that they have ammassed a lot of fines by 
then, since they are long past their due-time.

Is there a way for us to either have time-based rules, or select 
between two different rule-sets at checkout?  Or is there some other 
approach that we can use so that we can set up a policy of that nature?

     - Tim Young