Categories/Subjects

• Most clients use either BISAC (US industry standard) or BIC (UK industry standard) codes to manage their categories.
• Occasionally, clients prefer to use their own set of custom categories instead, for example ONIX-held custom categories, thema
  
  You can chose to use single-tier or two-tier category functionality i.e. are you only interested in showing your top-level categories (e.g. "Architecture") - single-tier - or would you also like to pull through sublevel categories (e.g. "Architecture - Buildings") - double-tier.
  Your metadata need to be compiled correctly based on the category tier you'd like to use