Since 1916 there has been a recognized demand for a method of classification of orthopaedic literature inclusive enough to permit the proper collection and retrieval of all literature on the subject. Today, MEDLINE, available through the PubMed interface, has become the de facto standard for organization and retrieval of medical literature. The Medical Subject Headings (MeSH), used to provide indexing and assist in searching, are partly responsible for this standard. Understanding how MeSH is built and maintained may lead the user to a better understanding of how to use MEDLINE, and what to expect from the indexing of an article.


The purpose of this review is to provide an understanding of the organization of large quantities of indexed material, the indexing process and the considerations involved in developing an indexing vocabulary.

Where are we now?

Successful terminology development and use, a prerequisite for any sharing of information by electronic means, depends on both user (how the user is expected to use the system) and information (how the information is organized) models. MEDLINE has a simple user model and a simpler information model. The user is expected to determine what is relevant and which MeSH descriptors are appropriate.

Where do we need to go?

While MEDLINE through PubMed is a success as viewed by the number of hits, further improvements will depend on better, faster indexing with a controlled terminology. Terminology development requires careful consideration of the nature of the subject, how users employ the terminology, the overall purpose of the terminology, and the framework of the systems in which it is used.

How do we get there?

For the future, understanding terminology development might enable the user to comprehend some of the issues involved in sharing of other information by electronic means. Further improvements in the availability and accessibility of medical literature will depend on continued maintenance and development of MeSH, as well as on refinement of the indexing process.

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