Placards
This might seem a strange question but...
Does anyone know the legal status of a restriction which is placarded in the cockpit (and there is a requirement in the POH for the placard to be there) but is not a restriction contained in the POH? Is there any requirement to comply with a placard? Assuming the placard came from a modification, can a modification impose a restriction itself or does the restriction have to be documented in the POH to be valid?
Before anyone points it out, I realise of course that there are safety issues in ignoring a placard which is no doubt there for a good reason. I am just interested in the strict legal position.