British Museum Cataloguing Rules:

British Museum, Department of Printed Books. Rules for compiling books, maps and music in the British Museum. - Rev. ed. - London: British Museum, 1936. printed by order of the Trustees. 

In 1757, the Royal Library (merged earlier in 1753 with Cottonian, Harleian and Sloan Collections) was transferred to the British Museum. The library's total stock of books at this time touched 5,00,000 mark. Since the previously compiled catalogues of the British Museum (Librorum Impressorum qui in Museo Britanico Ad servantur Catalogus, compiled by P.M. Many, S. Harper and S. Ayserough, published in 1787) and the other collections were poorly planned and not well executed lists, the trustees wanted to have a fresh alphabetical catalogue along with an additional general classed catalogue compiled. Accordingly, between 1813 and 1819 seven volumes of alphabetical catalogue (updation of 1787 Librorum) were issued. Sir Henry H. Baber was the keeper of printed books at this time. The general classed catalogue had to be planned and executed. Thomas H. Horne made a convincing presentation of a scientific classification in his Outline for the Classification of the Library (submitted to the trustees in 1825). He was therefore engaged, for a time, to accomplish the task. The project, however, failed and it was suspended in 1834. But his ideas on classification and rules for bibliographic description, especially, as they related to content notes, forms of authors' namesand indexes for classified catalogue proved valuable addition to the literature on cataloguing. Baber, as the keeper proposed a general alphabetical author catalogue and suggested that Panizzi be entrusted with the task of editing-it. He formulated sixteen rules for guidance and suggested the use of uniform slips for entries so that their arrangement and preparation of the manuscript for printing would prove easy. Baber's rules required entry under author if it appeared either on the title page or elsewhere within the book, the form of the name taken on the same basis. Anonymous works were to be entered under the prominent or the first word (not an article or preposition) of the title with possible author's name added after the title within brackets. Pseudonymous works, similarly required entry under the pseudonym with real name added at the end of the title within brackets. Collections were to be entered under editor and translations under original author. 

The current emphasis on scientific classification with Home's advocacy of classified catalogue on one hand, and the adherence to the tradition with Baber's insistence on alphabetical catalogue supported also by Panizzi on the other, ensued a spate of debates and arguments, of course, with no decisive results. Baber's proposal for a new alphabetical catalogue was finally approved by the trustees in 1838 with the stipulation that it should be completed by 1840 and, instead in the shelf by shelf order (as was originally suggested by Baber and Panizzi), the catalogue was to be completely alphabetized and issued in separate volumes for each letter of the alphabet. Panizzi was directed to write the rules for its compilation. 

Thus, came the famed British Museum Cataloguing Rules known also as Panizzi's 91 Rules. In fact, Panizzi did not author the rules all alone and entirely by himself. The code was the result of collaboration involving the concerted efforts of Edward Edwards, J.W. Jones, J.H. Parry and Thomas Watts besides Sir Anthony Panizzi. Each one first compiled a code individually which were then collectively studied and criticised to formulate rules by consensus so as to reflect the best in the cataloguing philosophy of the time. Initially 79 rules were formulated which were expanded to 91 rules in the final code published in 1841. 

These rules, clearly, were written to provide for the catalogue of one larger library, the British Museum. They were not intended to he of general use, i.e., use in other libraries. Because both the compilation of the catalogue and the formulation of the rules proceeded side by side, the first volume of the catalogue issued in 1841 proved unsatisfactory, marred by many omissions. Obviously, the rules were applied partially. ,A rash of criticisms and enquiries followed requiring Panizzi to defend the rules. He questioned the feasibility of the project of a printed catalogue for such a large library as the British Museum Library. His testimony before the commissions presenting his views was considered to constitute not only an excellent notes to the rules but also a remarkable introduction to the foundations of cataloguing. The testimony covered many topics of recurring interest, such as, optimal level of bibliographical description and the relation of description to the objectives and functions of library catalogue; normalisation of names of persons and corporate bodies; problems of transliteration, title page transcription, etc.; entry for different forms of publications; treatment of modifications, adaptations, etc. of original works, anonymous publications, etc.; consistency and uniformity in application of cataloguing rules; nature of cross references; filing and arrangement of entries, and so on. It is perhaps for this reason that Panizzi's name came to be identified rather singly with the formulation of the rules. The job was entrusted to him and he led the team.  

The printing of the catalogue was given up with the first volume. However, the manuscript project continued. In 1849, a guard book catalogue with entries copied on slips mounted on to the pages of large registers was devised which resulted in a 150 volume catalogue in 1851. Panizzi contended that author catalogue served the users the best, because, according to him most users preferred author approach as the basic approach. The rules therefore, provided for author catalogue with an index of matter (alphabetical subject index based on the subject words picked up from titles) appended to it. The printed catalogue (in book format) cannot admit (fully descriptive) multiple entries lest it becomes impossibly bulky. As a measure of check against the bulk, one entry per book was the answer. Panizzi assumed that this single entry (under author) with sufficient description should serve as the principal/main entry with references (in lieu of added/additional entries) made to it.