The line type timing source for this entry. If the
juniSystemTimingSourceType object is not timingLine(3), then reading
this object will return timingSourceLineUndefined(0). The agent will
not accept a set to this object unless the juniSystemTimingSourceType
object is set to timingLine(3). Attempting to set this object to
timingSourceLineUndefined(0) will always return an inconsistantValue
error. Attempting to set this object to a value that is not supported
on the type of system running the agent will result in an
inconsistantValue error.