Searching the SDI System Against User Profiles
As has been mentioned earlier, the user profile attempts to represent not only the user's subject interests but also his search preferences as well as search patterns. Let us try to analyse as to how searches are carried out in SDI System.
A search tenth in a search profile can be a single word, a sequence of words in a string, an author's name, the name of an institution, the title of a journal, a subject heading and a classification code. It may occur in the reference as a description both of the contents of the document and of the document itself, the title of the source publication, organisation, report number, patent number, etc. Its some systems, the terms are restricted to those of a thesaurus compiled for that system'. The information professional constructs the search profile by selecting the search terms from the thesaurus' and other reference tools. In a thesaurus, we generally find synonyms, general definitions, specific definitions, related terms (RT) and narrower terms (NT): The thesauri also provide certain used for' terms (UF).
As the search is performed by matching the contents of the database (document profile) with search terms in the search profiles, all the variations in spelling have to be considered (e.g., gaging, gauging, etc). Both letters and numbers are searched in order to retrieve as many relevant references as possible. To enable this, the list of search terms in a search profile has to he exhaustive. For SDI to be selective, it has to be matched against the known subject interests of the individual (i.e., a subject profile) so that the user receives only that information which is relevant, The main aim of SDI is to save the user's time by not providing material which is of no interest to him/her. In order to do so search strategy consisting of the users interests (expressed in relevant terms must be created and stored.