A bit mask signifying what portion of the
specified ATM address is relevant. If the ATM address
is not specified (i.e. at row creation time), then
this object defaults to all zeros (no portion of the
lecsAtmAddrSpec value is relevant). If the ATM
address is specified but this object omitted at row
creation then this object defaults to all ones (all of
the specified lecsAtmAddrSpec value is relevant).
This object cannot be specified at row creation time
without also specifying a value for the
lecsAtmAddrSpec object. When the LECS is configured
to have one ATM address (one entry in this table),
modifying this object will result in the LECS
reinitializing and dropping all connections to it.