Regularity of publication and distribution are desirable in periodicals. Long suspensions in publication are a cause to reconsider the value of an existing subscription. Backfiles A backfile is not automatically created for every title to which the library subscribes. The factor of indexing becomes very important in determining whether a backfile will be created for a title. Periodicals that are not indexed at all, or that are cited in indexes not owned by the library, or that are not accompanied by their own index are not good candidates for backfiles.
Indexing is also a consideration in the purchase of large backfiles.
Such purchases are rare, however, and are usually made for specific reasons that outweigh the importance of indexing. Large backfiles are generally purchased in order to fill a major gap in an existing backfile, to improve a conspicuously underdeveloped subject area which is part of the university's curriculum, to support a major new program, or to meet professional accreditation standards. Backfiles may be in paper, in microform, or in electronic format. Microform backfiles will generally be all on microfilm or all on microfiche. Last edited May 6, 1996.