Two Enumerators on one class?

Question

Hi all, I'm writing a shift planning system and have a class for Department. The Department contains two lists (workers and shifts) over which I wish to iterate. Can I do this without exposing the unlying list-objects (workers and shifts) and iterating over them? Given a solution that lets me iterate over the Department in two ways - would that be the recommended method over simply exposing the two lists? Thanks for any comments, Anders My code - a rather large zip, 7Mb: http://www.juul.brygge.dk/OpenSource