On the origins of the word « etiquette », both in French and English :

It happened in the reign of Louis XIV, when the gardens of Versailles were being laid out, that the master gardener, an old Scotsman, was sorely tried because his newly seeded lawns were being continually trampled upon. To keep trespassers off, he put up warning signs or tickets—etiquettes—on which was indicated the path along which to pass. But the courtiers paid no attention to these directions and so the determined Scot complained to the King in such convincing manner that His Majesty issued an edict commanding everyone at Court to "keep within the etiquettes."

By Richard Duffy, from the Introduction to the book Etiquette in Society, in Business, in Politics and at Home by Emily Post, 1922.