-L<strtoll(3)>. B<CounterInc> and B<DeriveInc> do not use the submatch at all
-and it may be omitted in this case.
+L<strtoll(3)>. B<CounterInc>, B<DeriveInc> and B<GaugeInc> do not use the
+submatch at all and it may be omitted in this case.
+
+The B<Gauge*> types, unless noted otherwise, are reset to C<NaN> after being
+reported. In other words, B<GaugeAverage> reports the average of all values
+matched since the last metric was reported (or C<NaN> if there was no match).