The MIB module defining objects for the management of a pair of
ADSL modems at each end of the ADSL line.  Each such line has
an entry in an ifTable which may include multiple modem lines.
An agent may reside at either end of the ADSL line however the
MIB is designed to require no management communication between
them beyond that inherent in the low-level ADSL line protocol.
The agent may monitor and control this protocol for its needs.

ADSL lines may support optional Fast or Interleaved channels.
If these are supported, additional entries corresponding to the
supported channels must be created in the ifTable. Thus an ADSL
line that supports both channels will have three entries in the
ifTable, one for each physical, fast, and interleaved, whose
ifType values are equal to adsl(94), fast(125), and
interleaved(124), respectively. The ifStackTable is used to
represent the relationship between the entries.

Naming Conventions:
          Atuc - (ATUC) modem at near (Central) end of line
          Atur - (ATUR) modem at Remote end of line
          Curr - mandatory
          Prev - Previous
          Atn - Attenuation
          ES  - Errored Second.
          LCS - Line Code Specific
          Lof - Loss of Frame
          Lol - Loss of Link
          Los - Loss of Signal
          Lpr - Loss of Power
          xxxs- interval of Seconds in which xxx occurs
                 (e.g., xxx=Lof, Los, Lpr)
          Max - Maximum
          Mgn - Margin
          Min - Minimum
          Psd - Power Spectral Density
          Snr - Signal to Noise Ratio
          Tx  - Transmit
          Blks- Blocks, a data unit, see
                 adslAtuXChanCrcBlockLength
  
Build from Initial Version, published as RFC 2662