Compatibility of cataloguing rules is as essential as compatibility of formats. While formats govern the structure of metadata, cataloguing rules govern its content.

Two events marked the start of international initiatives on the definition of compatible cataloguing rules:

  • 1961, the Paris Principles made recommendations on the choice, form and structure of headings for names and for titles
  • 1969 the IFLA International Meeting of Cataloguing Experts held in Copenhagen (Chaplin, Anderson & Honoré, 1970) produced a resolution that proposed creation of standards to regularise the form and content of bibliographic descriptions.