This trigger expression works as follows:
1. It can be triggered if the operational status is "down".
2. `{$PAN.PA440.IF.HW.CONTROL:"{#IFNAME}"}=1` - a user can redefine the context macro to "0", marking this interface as not important. No new trigger will be fired if this interface is down.
3. `last(/TEMPLATE_NAME/METRIC)<>last(/TEMPLATE_NAME/METRIC,#2)` - the trigger fires only if the operational status has changed to "down" from some other state (it does not fire for "eternal off" interfaces).

WARNING: if closed manually - it will not fire again on the next poll because of `last(/TEMPLATE_NAME/METRIC)<>last(/TEMPLATE_NAME/METRIC,#2)`.