Selects whether the interface will be used primarily as as
timing provider for other interfaces on the same board. This
object is applicable only if the interface supports reference
locking, i.e. if the `ref' bit is set in itsIfCapabilities.
no(0). Used primarily as normal transport interface and
secondarily as digital timing provider. Operational state is
non-dormant and alarms are raised only when ingress or egress
connection exists.
wordClock(1). Used primarily as 48 kHz word clock timing
provider. Neither ingress nor egress connections are
allowed. Operational state is non-dormant and alarms can be
raised if needed.