appellation vs code name

appellation

noun
  • A name or title by which someone is addressed or identified; a designation. 

  • A geographical indication for wine that describes its geographic origin. 

code name

noun
  • A name used to clandestinely identify somebody or something, either for military or espionage purposes, or for commercial confidentiality. 

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