The files listed are included in your COMSOL session. This means that your interfaces appear in the Model Wizard, so you can add them to your model and work with them like any other physics interface. You can also save model files (*.mph) that use your new interface. To add a development file, right-click the Development Files node () and choose Add Builder File. If you right-click any added development file, you can choose to remove it from the list or to open it. There is also an option to compact the archive. The compact operation removes all unnecessary data in the file to save space and simplify textual comparisons between different versions of a file.

Whenever you make changes to a builder file listed as a development files, you must click the Register Development Files toolbar button () to re-read all files into the current session.