coda vs postscript

coda

noun
  • A conclusion (of a statement or event, for example), final portion, tail end. 

  • The optional final part of a syllable, placed after its nucleus, and usually composed of one or more consonants. 

  • In seismograms, the gradual return to baseline after a seismic event. The length of the coda can be used to estimate event magnitude, and the shape sometimes reveals details of subsurface structures. 

  • A passage that brings a movement or piece to a conclusion through prolongation. 

postscript

noun
  • An addition to a story, play, etc. after its completion. 

  • An addendum to a letter, added after the author's signature. 

verb
  • To extend (a letter or another document) with additional remarks. 

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