Biology in 5A has to be only on Wednesday (or Biology cannot be on Wednesday)

If you want a particular lesson to be just on one day you can use this cardrelationship:

Basically it says you want 0 periods of biology in 5A on the marked days. Thus the Biology in 5A can only be on Wednesday.

Notes:
- this approach is better then locking, because there are 7 different positions the Bio can end up on Friday
- you could have created a new subject called "BioFriday" and set the time-off, but this approach is cleaner, no fake subjects.
- the same cardrelationship can be used to specify that Bio cannot be on Monday, just select Monday in the weekly grid.