if嵌套语句配对执行过程请求高手指点???

If (P_Process_Load_CV = Pro_LoadCV_LoadingComplete And P_Machine_LD_RunEnable = True)
  If (CMD_LDTF_LDCV_REMOVE_COMPLETE = TRUE And STATUS_LD_TF_LOAD_INTERLOCK = LOCK_OFF)
    If (STATUS_LD_CV_GLASS_EXIST = NONE Or P_RunConfig_Status = RunConfig_VIRTUAL)
      STATUS_LD_CV_GLASS_DATA   = NONE;  
      CMD_LDTF_LDCV_REMOVE_COMPLETE = FALSE;  
      O_SOL_LD_CV_PIN_UP = SOL_OFF      
      O_SOL_LD_CV_PIN_DOWN = SOL_ON
      TmrPinUpDown = P_Cyl_Move_OverTime;
      While (TmrPinUpDown > 0)
        If (I_SEN_LD_CV_PIN_UP = SEN_OFF And I_SEN_LD_CV_PIN_DOWN = SEN_ON)
          TmrPinUpDown = 0;
        EndIf
      EndWhile
      If (I_SEN_LD_CV_PIN_UP != SEN_OFF Or I_SEN_LD_CV_PIN_DOWN != SEN_ON)
        STATUS_ERROR_CODE = ERROR_PIN_DOWN_TIMEOVER
      EndIf
      P_Process_Load_CV = Pro_LoadCV_LoadingReady;
      
    Else
      STATUS_ERROR_CODE = ERROR_LD_CV_GLASS_EXIST;
    EndIf
  EndIf
EndIf

CLOSE

最好请说明程序执行的过程是怎么样子的 IF与ENDIF之间配对过程////??????