World Wide Web has enabled libraries to make their databases available to a vast world-wide audience. The situation is even more heterogeneous with portals and distributed/federated searching across different resources and services. But the principles of subject access (as known and developed in libraries) can be applied to any of these situations. Subject access has been identified as important to the majority of intended user groups of national bibliographies and it is therefore essential to provide it efficiently. Difficulties in determining the precise proportion of subject searches are attributed to users regularly using uncontrolled “keywords” derived from the descriptive metadata to undertake their subject searches
Guidelines for subject access to national bibliographies were prepared by a working group of IFLA’s Classification and Indexing Section.