apostil vs clavis

apostil

noun
  • A marginal note; a gloss. 

  • A method of verification for international documents. 

clavis

noun
  • A glossary. 

  • A Roman key. 

  • A key; an identification guide; a series of logically organized groups of discriminating information which aims to allow the user to correctly identify a taxon. 

  • A device for restraint of the hands. 

How often have the words apostil and clavis occurred in a corpus of books? (source: Google Ngram Viewer )