whilst at the library, panizzi undertook the creation of a new catalogue, based on the "ninety-one cataloguing rules" (1841) which he devised with his assistants. these rules served as the basis for all subsequent catalogue rules of the 19th and 20th centuries, and are at the origins of the isbd and of digital cataloguing elements such as dublin core. panizzi had to give up his concept of "corporate main entry" to have his 91 rules code approved. panizzi's idea of corporate authorship later came to public attention through charles c. jewett's code for the catalog of the smithsonian institution in 1850.