To create a new schema file, click New in the toolbar or navigate to File > New Schema File. A tab titled 'Untitled1.asn' is displayed in the central editing area of the GUI.

Define the schema by copy/pasting text or by manually entering text between the "DEFINITIONS ::= BEGIN" and "END" statements in the file. When finished, click Save file in the toolbar or navigate to File > Save file or File > Save file as. Click Validate to check for proper syntax and to confirm that no errors are present. Upon validation, a success or failure message is returned in the Error Log.

To open an existing schema file for edit, click Open in the toolbar or navigate to File > Open File. The file is added to the project and is displayed as a tab in the central editing area. A schema file that is already included in a project can be opened by selecting the file name from the list of Schema/ASN.1 files in the Project pane.

At any point during editing, the schema can be saved and validated.

To remove a schema file from a project, right-click on the file name from the list of Schema/ASN.1 files in the Project pane and select Remove. Or, simply select the file within the Schema/ASN.1 files list and click Remove in the toolbar.