anchor.diff:  ==== Additional Attributes and Parameters
   
   The following Information Elements are defined in addition to those
  -specified in 3GPP TS 12.21 Chapter 9.4.
  +specified in 3GPP TS 52.021 Chapter 9.4.
   
   All of these additional IEs are _received_ by OsmoBTS.
   
   These attributes are not used by OsmoBTS, but
   simply passed to OsmoPCU connected to the PCU socket.
   
  -.Additional IEs handled by OsmoBTS but not defined in TS 12.21
  +.Additional IEs handled by OsmoBTS but not defined in TS 52.021
   [options="header",cols="5%,50%,45%"]
   |===
   | tag (hex) | IE name | Description
  
positive.code: [cols="30%,25%,15%,15%,15%"]
  |===
  | INFORMATION ELEMENT | REFERENCE | PRESENCE | FORMAT | LENGTH
  | Message Type | 3GPP TS 12.21 9.1 | M | V | 1
  | Object Class | 3GPP TS 12.21 9.2 | M | V | 1
  | Object Instance | 3GPP TS 12.21 9.3 | M | V | 3
  | GPRS Routing Area Code | <<NM_ATT_IPACC_RAC>> | O | TL16V | >= 4
  | GPRS Paging Configuration | <<NM_ATT_IPACC_GPRS_PAGING_CFG>>  | O | TL16V | >= 5
  | GPRS RLC Configuration | <<NM_ATT_IPACC_RLC_CFG>> | O | TL16V | >= 12
  
negative.code: | 0x47 | 9.4.32 | Measurement Result  |  | _ignored_
  |===
  
  ==== IEs Not Conforming to TS 52.021
  
  .IEs not conforming to TS 52.021
  [options="header",cols="5%,10%,30%,55%"]
  |===
  | tag (hex) | TS 52.021 § | IE name | Description
  | 0x15 | 9.4.21 | HSN              | presence causes NACK response
  | 0x17 | 9.4.23 | HW Description   | _ignored_ by OsmoBTS, but coding may differ, see <<ie_hw_desc>>
  | 0x1b | 9.4.27 | MAIO             | presence causes NACK response 
  