function clear_previous() {
  previous.bs = '-';
  previous.dst = '-';
  previous.wp_name = '-';
  previous.course = -999;
}
// clear the attributes that control the display refresh
clear the attributes that control the display refresh
clear the attributes that control the display refresh
function clear_previous() {
  previous.bs = '-';
  previous.dst = '-';
  previous.wp_name = '-';
  previous.course = -999;
}
function clear_previous ( ) { previous . bs = '-' ; previous . dst = '-' ; previous . wp_name = '-' ; previous . course = - 999 ; }
clear the attributes that control the display refresh
clear the attributes that control the display refresh