For TAPER, beam sizes and noise level (in flux and brightness) will be computed for 9 different tapers (from Start to Start*Step9̂). Default value for Step is sqrt(2), Default value for Start is 50 m. Weighting mode, UV cell size and "robust" parameter are taken from variable MAP_UVCELL and MAP_ROBUST (i.e. one can combine Robust weighting and Tapering).
The /PLOT option will display the inner regions of the beams.