anchor.diff:  .3+.| 8.9.2 | 0x74 .3+.| <<opstart>> | Opstart | <- | Received
               | 0x75                   | Opstart Ack | -> | Sent
               | 0x76                   | Opstart Nack | -> | Sent
  +6+<| *Other Messages:*
  +.3+.| 8.11.1 | 0x81     | <<get_attributes>> | Get Attributes         | <- | Received
  +    | 8.11.3 | 0x82     | <<get_attr_resp>>  | Get Attribute Response | -> | Sent
  +    | 8.11.1 | 0x83     |                    | Get Attributes Nack    | -> | Sent
   |===
   
   
  
positive.code: 
  This attribute is not used by OsmoBTS, but
  simply passed to OsmoPCU connected to the PCU socket.
  
  === A-bis OML Initialization / BTS bring-up
  
  
negative.code:     | 8.10.3 | 0x8C | Stop Measurement
      | 8.10.4 | 0x8D | Start Measurement
  3+<| *Other Messages:*
  .3+.| 8.11.2 | 0x84 | Set Alarm Threshold
               | 0x85 | Set Alarm Threshold Ack
               | 0x86 | Set Alarm Threshold Nack
  