The DYA program controls access to all DYABOLA databases. It is neither a database engine, nor the actual database. Rather, it is a control program with which the data in a database can be structured, administered, searched and browsed through. By combining relational and hierarchic elements, the program meets the demands of the sciences of art and culture. In contrast to other programs, the most complex of data systems can be created, but they remain easily and quickly accessible and allow all imaginable questions, due to the simplicity of the program. The aim of this manual is to fully explain the program's search and navigation functions. In addition, it should show the possibilities offered by the program's open structure. These possibilities have been exploited differently in the various DYABOLA database projects. In some cases, there are even contradictory data structures, in order to meet the respective requirements of the database. The open structure of DYABOLA makes it possible to adapt a database project to the method of working of the operators (librarians, archivists…) or to the material conditions (e.g. overlapping, incompatible inventories). It is of course possible to take up standard data or specified partial structures such as official thesauri into DYABOLA databases. However, the real strength of the program is the lack of a need to force a predefined amount of data into the system of standard data, which would inevitably lead to a loss of valuable data. This manual deals with the basic components of a DYABOLA database and the installation and functions of the search program. Please refer to the introductory manuals on the individual database projects for the various different types of search and navigation. In contrast to the introductory manuals, this manual is intended to serve as a reference work for the user of a DYABOLA database who has already gained an insight into the functioning of a program. It should give the user the chance to grasp the structure of a DYABOLA database in order to gain the greatest possible benefit from it.