// ********************
// ***  Slot class  ***
// ********************

   New Slot AttributeBits mask:
     AltInputSlotBit = 0x20000,

   // *** Alternate Input Slot Mode Support ***

   // Alternate Input Slot Mode is currently supported only on SeriesSlots.
   // SeriesSlots can have alternate inputs provided by either a 
   // PeriodicSlot or a ScalarSlot.

   typedef enum {
      AltInpMode_Series = 0,
      AltInpMode_Periodic,
      AltInpMode_Scalar
   } AltInpMode;

   // For SeriesSlots using child Alternate Input Slots
   virtual bool altInputSlotModeEna() const { return (false); }
   virtual bool hasAltInputSlots()    const { return (false); }
   virtual AltInpMode altInpMode()    const { return (AltInpMode_Series); }
   virtual PeriodicSlot* altInputPeriodicSlot() const { return (NULL); }
   virtual ScalarSlot*   altInputScalarSlot()   const { return (NULL); }

   // For Slots which are Alternate Input Slots
   bool isAltInputSlot() const {
      return ((attributeBits & AltInputSlotBit) != 0); }
   virtual SeriesSlot* isAltInputForSeriesSlot() const { return (NULL); }

// **************************
// ***  SeriesSlot class  ***
// **************************

    // Alternate Input Slot Mode Support
    bool          _altInpModeEna;
    AltInpMode    _altInpMode;   
    PeriodicSlot* _altInpPeriodicSlot;  // ownership
    ScalarSlot*   _altInpScalarSlot;    // ownership

public:
    // Alternate Input Slot Mode Support
    bool          altInpModeEna()      const { return _altInpModeEna; }
    AltInpMode    altInpMode()         const { return _altInpMode; }
    PeriodicSlot* altInpPeriodicSlot() const { return _altInpPeriodicSlot; }
    ScalarSlot*   altInpScalarSlot()   const { return _altInpScalarSlot; }

    void setAltInpModeEna (bool);
    void setAltInpMode (AltInpMode);
    void dropAltModeSlots();

private:
    void checkCreateAltInpPeriodicSlot();
    void checkCreateAltInpScalarSlot();

// ******************************************
// ***  Periodic and Scalar Slot classes  ***
// ******************************************

    // Alternate Input Slot Mode Support
    SeriesSlot* _altInputForSeriesSlot;   // not ownership

  public:
    // Alternate Input Slot Mode Support
    // virtual from Slot
    virtual SeriesSlot* isAltInputForSeriesSlot() const 
    void setAltInputForSeriesSlot (SeriesSlot* sslot);

---