If not used carefully, relevant as well as irrelevant articles will be lost. Operators indicate to the search engine how words, character strings, or Sets will be related during the search processing. And , Or , Not search for words across Fields or sets of records , while the proximity operators such as adjacent and near search for words in the same field. Or is an operator that is used to combine similar words or sets into a single set. The resulting set will be larger than any of the sets you started with.
Records are the units that make up a database.
Records consistently describe the attributes of an article by breaking down information into a structure of Fields . Root is a command that displays the index of the entire database at the point that most closely matches the word typed. Also called Neighbor or Index. A database such as Medline has been loaded into numerous search engines. Examples are Ovid, Silverplatter, Paper Chase, Dialog, and Medlars.