In PowerDesigner, you can define a generated file on a selected metaclass (or stereotype or criterion), in this case a file is generated for each instance of the metaclass existing in your model.
The generated files mechanism is defined in Customizing and Extending PowerDesigner > Extension Files > Templates and Generated Files (Profile).
You can modify the default generation of files using artifacts. Artifacts are used to generate files only for selected instances of a metaclass in order to:
Artifacts are visible in the C# and VB .NET object languages. This is to support round-trip engineering for these languages: when you reverse engineer C# or VB .NET code, each source file in the source code becomes an artifact in PowerDesigner. The artifact allows you to re-generate the same collection of objects while preserving file structure.