[Al_The_Man]

That is what I meant by my first sentence, maybe not very clearly, What I meant was it is the condition that it is in when it performs the function of its description, as in the example, the name of the switch or input is Over Travel Switch.
So if I describe the machine over travels as being active low, it usually means that the logic is looking for a 0 when the overtravel occurs.
Probabally a case of semantics, but it can be important if you are writing the logic for the function.
Some Manuf. indicate a active low input required by placing an Asterisk in front of the input descriptions and designated input number .
Al.