seeking help on how to populate a timetable with restrictions

Hi

I have an example of a completed timetable for a group of students - see attached

My question:

Is it possible to present a supervisor with an empty timetable such as shown

The supervisor starts to enter information in a cell in the timetable

1) If the cell is in a weekend, then only codes such as AW/WN, AW/HV etc. can be entered

2) If the cell is in a week, then many more codes are possible e.g. IP/WN, OP/HV, Surg, Well, 'Neon, Well' etc.

Is it possible to setup two drop down lists as per (1) and (2) so that when the supervisor clicks on a cell, they are presented with one of the two drop down lists
Thus controlling exactly what may be entered into each cell in the timetable ?

Thanks for any pointers..........

Bob M