DataViewx data removal
======================
        
          * To eliminate data from the working data set:

            1. press control-button-3 at one corner of the region to eliminate.

            2. hold the button down and move to the opposite corner of the
               erase region.

            3. release control-button-3.
               data points within the erase region are eliminated from the
               working data set.
               **NOTE**: the x- and y-columns must be selected to
               correspond to the curve which is used for the
               removal operation.

          * To restore the data eliminated by erase operation(s).

            1. File->Restore Data

          * To accept the data eliminated by erase operation(s) into
            the backup data set.

            1. File->Accept Data