====Changed====

The **Changed** function is part of the [[Trigger]] class. 

It returns //true// if any of the value(s) have changed between now and the last time the trigger was executed (ie. the last time the function returned 'true').

The function has an //optional// parameter. If **False**, this function will return true //even if the data value is bad, invalid or empty//.

If the optional parameter is **True**, then the function won't consider a change from a valid value to an invalid or empty value a genuine change. This prevents the trigger system from firing when there's a temporary outage in the middle of a batch or cycle.