The two objects h3cDot3OamErrSymPeriodWindowHi and
h3cDot3OamErrSymPeriodLo together form an unsigned 64-bit
integer representing the number of symbols over which this
threshold event is defined. This is defined as
h3cDot3OamErrSymPeriodWindow = ((2^32)*h3cDot3OamErrSymPeriodWindowHi)
+ h3cDot3OamErrSymPeriodWindowLo
If h3cDot3OamErrSymPeriodThreshold symbol errors occur within a
window of h3cDot3OamErrSymPeriodWindow symbols, an Event
Notification OAMPDU should be generated with an Errored Symbol
Period Event TLV indicating the threshold has been crossed in
this window.