Periodical database indexing is closer to cataloguing, as database indexers usually choose terms from a controlled vocabulary, although they may also be able to add uncontrolled terms and create new controlled terms as needed. Occasionally the same controlled vocabulary is used for indexing and cataloguing. Indexers who are also librarians are most likely to be influenced in their decisions by AACR2 rules. There is also a significant difference in the career options of indexers and cataloguers. Cataloguers have traditionally worked in libraries, often in groups.
Some cataloguers work for companies which provide a cataloguing service to libraries.
Indexers, on the other hand, tend to be freelancers working alone, and often combine indexing with some other work. There are a few full-time indexers in Australia, working as freelancers or for publishing companies or other organisations. As more cataloguing is contracted out by libraries, there will be more opportunities for cataloguers to set up their own companies, or to work as freelancers. The loss suffered by cataloguers when work is contracted out by their library against their will, may be balanced to some extent by the gains of the entrepreneurial cataloguers who pick up the work. It is also probable that indexers will find that the nature of their work changes.