+I<smoothing-window> specifies the fraction of a season that should be
+averaged around each point. By default, the value of I<smoothing-window> is
+0.05, which means each value in SEASONAL and DEVSEASONAL will be occasionally
+replaced by averaging it with its (I<seasonal period>*0.05) nearest neighbors.
+Setting I<smoothing-window> to zero will disable the running-average smoother
+altogether.
+