This is a bit map representing the breaker poles within the
module that are associated with this distribution cable.
The following 3 bits are used to indicate the indices of
the breakers feeding the cable:
b0 - Module breaker L1
b1 - Module breaker L2
b2 - Module breaker L3
If a bit is set, the breaker is used to feed this distribution cable.
These breakers are described in the table isxModularDistModuleBreakerTable,
and indexed by the OID isxModularDistModuleBreakerPhaseIndex.