function range_control, range, $
   reset=reset, start=start, stop=stop, current=current
;
;+
;-
; range=array(2,4)
;
if keyword_set(reset) then range(*,1)=range(*,0)
if keyword_set(start) then range(0,1)=range(2,1)
if keyword_set(stop)  then range(1,1)=range(2,1)
if keyword_set(current) then range(2,1)=current
return,range
end