multiple entries / multiple criteria
 

Hello, I could use some help on this one. I am trying to make a scheduling
sheet that will look for multiple entries but also not allow certain entries.
For example, I have a column "Tuesday" that has "sections" of 3 cells each.
They are all drop down lists. In each section, there is a main heading. The
first is 1A. In row 2, you select a name, row 3 a time (either 1st 2 hours,
2nd 2 hours, or all 4 hours), and in row 4 you select a room number. The next
"section" would be 1B which would also have the same 3 dropdown lists, etc..
So let's say Joe is scheduled on Tuesday for a 1A class for the 1st 2 hours
in room 1. In order for him to work in a 1B class also, he would only be able
to work the 2nd 2 hours. So, if someone tried to schedule him for a 1B class
for the 1st 2 hours, they would get an error message saying he's already
working the 1st 2 hours in another class. Or if he were scheduled for the 1A
for all 4 hours, he would not be available to work any other classes for that
night. I hope this makes sense. I'm stuck at this point. Thanks for any
advice, -Kevin