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   The first phase of an application development is the definition of the
   Data Dictionary, i.e. the creation of files, relative fields, indexes
   associated and relations. From the main menu, use the Dictionary
   button to access the definition environment of the data dictionary.

   This is the most delicate phase of the development cycle. The definition
   of a correct data structure can bring notable benefits to the project
   being created. A wrong setting of the data structures can cause the
   failure of a great portion of the project. We suggest to make a close
   preliminary analysis of the database's structure.

   The most critical activity of this phase is without any doubt the
   definition of the relations between the files and the corresponding
   referential integrity rules. The relations, specifying the connection
   between the various files of the database, are indispensable for the
   realisation of the functionalities of data entry and reporting objects
   that make up the skeleton of the project.

   A relation expresses the dependence that exists between the records that
   come from two involved files. The three types of relations available in
   dBsee 4 (1:N, 1:1 and N:1 relations) express the different ways in which
   the information coming from two different files can be connected.

   The referential integrity rules allow to specify the update mode to use in
   order to maintain the consistency of the entire database when data from a
   file is deleted or modified. Using the relations and the integrity rules
   can help avoid problems occuring in the data. For example, an order whose
   field Customer Code refers to an inexistent client is avoided.