Defines an entry in the tmnxOamPingHistoryTable. The first two
index elements identify the tmnxOamPingCtlEntry that a
tmnxOamMacPingHistoryEntry belongs to. The third index identifies
a specific run of the OAM test. The fourth index element
selects the group of responses associated with a specific probe
attempt. The fifth index selects a single OAM 'macPing' reply.