bar line vs oblique mark

bar line

noun
  • Synonym of crossline (“type of headline”) 

  • A vertical line in musical notation used to separate two bars or measures. 

oblique mark

noun
  • Synonym of slash ⟨/⟩, sometimes (generally proscribed) inclusive of similar marks such as the backslash ⟨\⟩. 

How often have the words bar line and oblique mark occurred in a corpus of books? (source: Google Ngram Viewer )