DIRA2 is a software structure that allows the astronomer to manage in a simple and articulate way the astronomical data files, especially catalogues. The users can access this structure by a set of commands that activate specific procedures.
DIRA2 allows the creation and the management of a catalogue data base, either of general or private use (master and personal data base respectively). The manipulation of files, the extraction of subfiles by user defined criteria, and the iconographic view of the results are supported by the command set.
For special user applications, a FORTRAN library exists that uses the same philosophy and the same conventions. The FORTRAN calls are described in the "PROGRAMMING in DIRA" manual.
The main feature of the DIRA2 philosophy is that the catalogues and the variables, (e.g. Right Ascension, Declination, Magnitude etc ) are known to the system by conventional codes defined in a vocabulary. This means, in practice, that if one is interested on a list of magnitudes from the Uppsala General Catalogue, he needs to enter the keywords "UGC" and "MAG", besides, of course, other minor specifications on output etc
About 140 catalogues are presently available in DIRA2. The users can insert other catalogues with a minimal effort. All the commands provide default values and have an help structure.