TOXLINE: evolution of an online interactive bibliographic database.

The National Library of Medicine has offered TOXLINE, an online interactive bibliographic database of biomedical (toxicology) information since 1972. Files from 11 secondary sources comprise the TOXLINE database. The sources supplied bibliographic records in different formats and data structures. Data from each supplier's format had to be converted into a format suitable for TOXLINE. Three different, successive retrieval systems were used for the TOXLINE database which required reformatting of the data. Algorithms for generating terms for inverted file search methods were tested. Special characters peculiar to the scientific literature were evaluated during search term generation. Developing search term algorithms for chemical names in the scientific literature required techniques different from those used for nonscientific literature. Problems with replication of bibliographic records from multiple secondary sources are described. Some observations about online interactive databases since TOXLINE was first offered are noted.