The Structure File Editor is a tabbed pane within the Data File Tools (Technology Preview) window that enables you to create and edit layouts within a structure file. The structure file can then be applied to a data file so that the Data File Editor is able to display the records within it in a way that makes them easier to view and edit.
Layouts are derived from the Data Division (level-01 fields and below in the File Section and Working Storage Section) of a COBOL program that uses the data file, and are created using the .idy file from the compiled program.
Structure files are not mandatory, but when applied to a data file, the fields within a record can be displayed in a structured way, making them easier to view and edit. If a structure file is not applied, the records are displayed unformatted, as long continuous strings of text, making them harder to view or update.
You can also use a structure file to save file details for file types that do not contain a file header. If you check the Save details check box on the Create New File dialog box, a .dfs file is saved containing the file details specified. This file is used to populate the File Details section the next time the data file is opened.
A structure file can contain both layouts and header details, but only layouts can be edited in the Structure File Editor.