The CDS/ISIS package indexes all fields selected for indexing into a single file. This file is known as 'inverted file'. There are indexing techniques for building index elements from lines, phrases enclosed in triangular brackets (< >) or slashes (/ 1) and from each word in the field. Non-significant words may be ignored by defining them in a stop work file. Once the new records are entered into the database, the inverted file must be updated so as to enable new records to be retrieved in searches. The CDS/ISIS allows you to select appropriate time for updating the inverted file.