why don;t many to many fields save in a .save(commit=False)

[MikeKJ]

Why don't manytomany fields save like this?

112                 af = editform.save(commit=False)
113                 af.level_1 = level_1
114                 af.level_2 = level_2
115                 af.level_3 = level_3
116                 af.level_4 = level_4
117                 af.save()

alternatively is there a way to insert the af.level(s) into the QueryDict in the POST and therefore not need the commit=False?