countersignature vs permission

countersignature

noun
  • A signature made to confirm or endorse another. 

permission

noun
  • authorisation; consent (especially formal consent from someone in authority) 

  • The act of permitting. 

  • Flags or access control lists pertaining to a file that dictate who can access it, and how. 

verb
  • To grant or obtain authorization for. 

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