The value of tmnxBsxStatAaSubCfgExportMethod specifies the method used
to export subscriber statistics.
When tmnxBsxStatAaType has a value of 'chargingGroup(4)',
a value for tmnxBsxStatAaSubCfgExportMethod must be supplied during row
creation.
Otherwise, upon row creation, tmnxBsxStatAaSubCfgExportMethod will have
by default only the 'accountingPolicy(0)' bit set.