A catalog (or catalogue — the former spelling is infrequently found in British writing but is fairly common in America), in general, is an organized register of some set of objects (for example, books, works of art, coins, car parts).
A library catalog is a register of all bibliographic items found in a library. A bibliographic item is a library material (for example, a book), a part of a library material (for example, a single novel in an anthology), or a group of library materials (for example, a trilogy), as far as it is relevant to the catalog.
Goal of a library catalog
A library catalog typically serves to answer the following questions:
- Does the library have a specific work?
- Which works by a particular author does the library have?
- Which works about a particular subject does the library have?
Some large libraries possess almost all publications of some period, or some country, and their catalog also serves to answer the following questions:
- Which works have been written by a particular author?
- Which works about a particular subject have been published?
In addition, a catalog may serve internal purposes of the library, for example as an inventory of everything that should be present.
Traditionally, there are the following types of catalog:
- Author catalog: a formal catalog, sorted alphabetically according to the authors' or editors' names of the entries.
- Title catalog: a formal catalog, sorted alphabetically according to the title of the entries.
- Keyword catalog: a subject catalog, sorted alphabetically according to some system of keywords.
- Mixed alphabetic catalog forms: sometimes, one finds a mixed author / title, or an author / title / keyword catalog.
- Systematic catalog: a subject catalog, sorted according to some systematic subdivision of subjects.
- Shelf list catalog: a formal catalog with entries sorted in the same order as bibliographic items are shelved.
Producing formal catalogs is relatively easy, as the cataloger can follow a set of cataloging rules. However, a formal catalog cannot answer question 3 (which works about some subject does the library have?). A subject catalog just serves that goal, but it is much more difficult to produce, as the cataloguer has to get an accurate impression of the contents of the bibliographic item.
Cataloging rules have been defined to allow for consistent cataloging of various library materials across several persons of a cataloging team and across time. Users can use them to clarify how to find an entry and how to interpret the data in an entry. Cataloging rules prescribe
- which information from a bibliographic item is included in the entry;
- how this information is presented on a catalog card or in a cataloging record;
- how the entries should be sorted in the catalog.
The larger a collection, the more elaborate cataloging rules are needed. Users cannot and do not want to examine hundreds of catalog entries or even dozens of library items to find the one item they need.
Currently, most cataloging rules are similar to, or even based on, the International Standard Bibliographic Description (ISBD), a set of rules produced by the International Federation of Library Associations (IFLA) to describe a wide range of library materials. These rules organize the bibliographic description of an item in the following areas: title and statement of responsibility (author or editor), edition, material-dependent information (for example, the scale of a map), publication and distribution, physical description (for example, number of pages), series, note, and standard number (ISBN).
Library items that are written in a foreign script are, in some cases, transliterated to the script of the catalog.
In a title catalog, one can distinguish two sort orders:
- In the grammatic sort order (used mainly in older catalogs), the most important word of the title is the first sort term. The importance of a word is measured by grammatic rules; for example, the first noun may be defined to be the most important word.
- In the mechanic sort order, the first word of the title is the first sort term. Most new catalogs use this scheme, but still include a trace of the grammatic sort order: they neglect an article at the beginning of the title.
The grammatic sort order has the advantage that often, the most important word of the title is also a good keyword (question 3), and it is the word most users remember first when their memory is incomplete. However, it has the disadvantage that many elaborate grammatic rules are needed, so that only expert users may be able to search the catalog without help from a librarian.
In some catalogs, person's names are standardized, i. e., the name of the person is always (catalogued and) sorted in a standard form, even if it appears differently in the library material. This standardization is achieved by a process called authority control. An advantage of the authority control is that it is easier to answer question 2 (which works of some author does the library have?). On the other hand, it may be more difficult to answer question 1 (does the library have some specific material?) if the material spells the author in a peculiar variant. For the cataloguer, it may incur (too) much work to check whether Smith, J. is Smith, John or Smith, Jack.
For some works, even the title can be standardized. For example, translations and reeditions are sometimes sorted under their original title. In many catalogs, parts of the Bible are sorted under the standard name of the book(s) they contain.
Many detail questions about alphabetic sorting of entries arise. Some examples:
- Some languages know sorting conventions that differ from the language of the catalog. For example, some Dutch catalogs sort IJ as Y. Should an English catalog follow this suit? And should a Dutch catalog sort non-Dutch words the same way?
- Some titles contain numbers, for example Orwell's 1984. How to sort them? (Often, it is decided to sort it as Nineteenhundred eighty-four.)
- [[Honor� de Balzac|de Balzac, Honor�]] or Balzac, Honor� de? [[Jos� Ortega y Gasset|Ortega y Gasset, Jos�]] or Gasset, Jos� Ortega y?
In a subject catalog, one has to decide on which classification to use.
On-line cataloging has greatly enhanced the usability of catalogs.
- The on-line catalog does not need to be sorted statically; the user can choose author, title, keyword, or systematic order dynamically.
- Most on-line catalogs offer a search facility for any word of the title; the goal of the grammatic word order (provide an entry on the word that most users would look for) is reached even better.
- Many on-line catalogs allow links between several variants of an author name. So, authors can be found both under the original and the standardised name (if entered properly by the cataloger).
Searching into OPAC
If you are looking for a book, you can access to the OPAC of your nearest library and search for it there.
If you want to look if a book exists and you have few elements to identify it, you can use a meta-searcher: you can fill the query form once and spread you search over many library catalogues. A service such as MultiOpac does this task for you.