The searcher asks another question, and the program supplies another number. Each query builds a set. Any set can be used again, usually just by typing the set number. The totality of these sets is the session history. The logical progression of retrieval, combination, limitation, display, selection and disposition of records is called the search strategy.
Sets persist until deliberately erased, or until the user exits the program.
Many databases allow searchers to edit, save and re-use search strategies. An interface is a structure of menus, prompts, default states or functions, HELP screens and other elements which allows users to search the database effectively without knowing the command line syntax used by expert level searchers. Systems designers try to combine menus and text in the best way to guide searchers to the next step in their session. They also provide clear links to HELP functions residing in the program. Treat any query as a subject search, unless told not to.