This adds or removes the current time series to the working set of climate indices. These will be shown when another time series or field is correlated with a time series.

So, in order to correlate a time series or field with a time series that is not in the standard set, one should first select the second time series, add it to the list of user-defined indices, next select the field or other time series and follow the link in the right-hand menu Correlate with a time series. The user-defined index should now appear in the list.

If the list becomes too long the one can remove indices from the list. Just select the time series, and the functio "add to list" should be replaced by the option to remove it.