public SeqCtrlOpt(SeqCtrlUse2 use,
                   SeqCtrlProceedOpt proceed = SeqCtrlProceedOpt.NOT_USED,
                   SeqCtrlNextOpt next       = SeqCtrlNextOpt.NOT_USED) : base(use, proceed, next)
 {
 }
 public SeqCtrlReqd(SeqCtrlUse2 use,
                    SeqCtrlProceedReqd proceed = SeqCtrlProceedReqd.NOT_USED,
                    SeqCtrlNextReqd next       = SeqCtrlNextReqd.NOT_USED) : base(use, proceed, next)
 {
 }
 public SeqCtrl(SeqCtrlUse2 use, T proceedReqd, U next)
 {
     Use     = use;
     Proceed = proceedReqd;
     Next    = next;
 }