indenture vs protocol

indenture

noun
  • A document, written as duplicates separated by indentations, specifying such a contract. 

  • A contract which binds a person to work for another, under specified conditions, for a specified time (often as an apprentice). 

  • An indentation; a recess. 

verb
  • To indent; to make hollows, notches, or wrinkles in; to furrow. 

  • To bind a person under such a contract. 

protocol

noun
  • The minutes, or official record, of a negotiation or transaction; especially a document drawn up officially which forms the legal basis for subsequent agreements based on it. 

  • A set of formal rules describing how to transmit or exchange data, especially across a network. 

  • The set of instructions allowing a licensed medical professional to start, modify, or stop a medical or patient care order. 

  • The official rules and guidelines for heads of state and other dignitaries, governing accepted behaviour in relations with other diplomatic representatives or over affairs of state. 

  • The official formulas which appeared at the beginning or end of certain official documents such as charters, papal bulls etc. 

  • An amendment to an official treaty. 

  • The first leaf of a roll of papyrus, or the official mark typically found on such a page. 

  • The original notes of observations made during an experiment; also, the precise method for carrying out or reproducing a given experiment. 

  • An accepted code of conduct; acceptable behaviour in a given situation or group. 

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