This object represents the value to be compared against. The
cwrThreshType determines the way in which it is used.
It is used as follows:
if cwrThreshType is ..
highThresh : Notify if data sample exceeds the cwrThreshValue.
lowThresh : Notify if data sample recedes below the cwrThreshValue.
upChange : Notify if data sample increases by more than
cwrThreshValue.
downChange : Notify if data sample decreases by more than
cwrThreshValue.
upLimit : Notify if data sample crosses cwrThreshValue while
increasing in value.
lowLimit : Notify if data sample crosses cwrThreshValue while
decreasing in value.