copybook vs error-free

copybook

noun
  • A series of instructions or data definitions copied into multiple programs from a shared library; boilerplate. 

  • A student's exercise book containing samples of good handwriting to be copied. 

  • A notebook containing blank, often lined, pages for writing answers. 

error-free

How often have the words copybook and error-free occurred in a corpus of books? (source: Google Ngram Viewer )