The value of tmnxVdoGrpSrcVqmStatsPeriod indicates the period of
statistics that the user is interested in. The parameter can take a
value of 'current' which would display to the user all statistics
within the last second. Alternatively it could a value of 'interval' in
which case the actual time-duration for which statistics are displayed
to the user is specified by MIB object 'tmnxVdoGrpSrcVqmStatsTime'.