The catalogues that form part of PDB can be modified with programs or editors. All types of corrections, additions, cancellation of records or fields are possible by PDB_MANAG.
It is necessary to keep in mind that files created with DIRA2 commands are in general files of fixed record length. On VAX/VMS the EDT editor creates files of variable record length that permit only a sequential access. Moreover fixed length record can not be handled with VMS/EDT, therefore you must use DB_UNFIX command to convert a file if you want to modify it. You can reconstruct a fixed length file by directly using the command DB_FIXA. In a Unix system the command DB_FIXA can be used to have the same length in all the records of a file created or modified by an editor.
When you detect an error in a big catalogue, it is better to use the DB_EDIT command to access wrong records; this command works on fixed files and makes a direct access to the record.
When the user modify a catalogue is better to run the DB_CHECK before starting to work with DIRA2 command to verify the new data set is suggested.