shilling mark vs slash mark

shilling mark

noun
  • Synonym of slash ⟨/⟩ in its use to mark the amount of shillings in a sum or (obsolete) in all its uses. 

slash mark

noun
  • Synonym of slash ⟨/⟩. 

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