In my limited experience I have found a few anomalies in wiring labels. I installed 2 thermostats/controllers for heating panels recently. The diagram in the written instruction leaflet,and the diagram printed on the stat, the wiring was correct...but on reading the instructions it reversed polarity...a simple typo really, but if you were reading it out to an apprentice of little brain, things would go wrong.
I brought this to the attention of the distributors, and they said they would "look into it", so that's fine!