It would be handy to be able to have a numeric bounds and to consider the item "unsupported" if it is out of bounds.

An example I have for you, to help you understand I have a temperature sensor.  In the SNMP mib it can also report humidity.  The sensor should only report temperature when polling but it also reports humidity as a -1 ("disabled").  With this feature, you would set the bounds of 0 - 100 (it is a percentage) and in this case the value would report as "not supported" would not be stored.

 

For the UI, I think A simple Checkbox "Enable Bound checking" and once enabled a "Upper Bound" and "Lower Bound" numeric box would be presented.

 

If you need more detail please let me know.