I<seasonal period> arguments agree.
I<alpha> is the adaption parameter of the intercept (or baseline)
-coefficient in the Holt-Winters forecasting algorithm. See L<RRDtool> for a
+coefficient in the Holt-Winters forecasting algorithm. See L<rrdtool> for a
description of this algorithm. I<alpha> must lie between 0 and 1. A value
closer to 1 means that more recent observations carry greater weight in
predicting the baseline component of the forecast. A value closer to 0 mean