[network_change_notify_descriptor.ChangeType]
Bits = 4
0x0 = Message only
0x1 = Minor - default
0x2 = Minor - multiplex removed
0x3 = Minor - service changed
0x4-0x7 = reserved for future use for other minor changes
0x8 = Major - default
0x9 = Major - multiplex frequency changed
0xA = Major - multiplex coverage changed
0xB = Major - multiplex added
0xC-0xF = reserved for future use for other major changes
