         Parameters:  [line# {0}] | [[previous# {1}] PREV]
  
 Sets  the  current-line pointer to the given line# or to the top
 if the line number is omitted.  The parameter  "PREV"  (or  "P")
 may  be  specified to set the current-line pointer to a previous
 position ("previous#" may be 1 to 5). 
  
 If "line#" points beyond the top of the file, the message  "TOP"
 is printed, and the current line is set to the top line. 
  
 If  "line#"  points  beyond  the bottom of the file, the message
 "BOTTOM" is printed, and the current line is set to  the  bottom
 line. 
