DEF KEYBOARD_INTERFACE Script {
      field    SFNode   me          USE KEYBOARD_INTERFACE
      field    SFInt32  oldMask     0
      field    SFNode   slide_set   IS slide_set
  
      eventIn  SFNode   onEvent
  
      field    SFInt32  previousKey 8
      eventOut SFTime   previous
  
      field    SFInt32  nextKey     32
      eventOut SFTime   next