public void Serialise(Writer Out)
{
Out.Write(Bookings.Count);
Bookings.ForEach(b => b.Serialise(Out));
Out.Write(Departments.Count);
Departments.ForEach(d => d.Serialise(Out));
Out.Write(Periods.Count);
Periods.ForEach(p => p.Serialise(Out));
Out.Write(Rooms.Count);
Rooms.ForEach(r => r.Serialise(Out));
Out.Write(Users.Count);
Users.ForEach(t => t.Serialise(Out));
Out.Write(Subjects.Count);
Subjects.ForEach(s => s.Serialise(Out));
Out.Write(Classes.Count);
Classes.ForEach(c => c.Serialise(Out));
}