I just bought a replacement AC Adapter and the warning printed upon it caught my eye.

Warning

(1)this device may notcause harmful interference

(2)this device must accept any interference received, including interference that may cause undesired operation.

1) The label is telling me that the adaptor will normally be harmful, but be careful, sometimes it may be harmless. (notcause is written as a single word)

2) I am not allowed to stop anyone touching my equipment, even if I know they are going to damage it.