5.12.4.4.  Create class system / Change current class system... (Classes and features)

5.12.4.4.1. Basic setting
5.12.4.4.2. Building/editing class system
5.12.4.4.3. Create features / Edit
5.12.4.4.4. Adjust sorting of classes and subclasses

Edit class system is the central dialog for editing class systems.

Edit class system" dialog box

Edit class system" dialog box

It appears initially via Tools [Extras] menu > Class systems: Edit... [Class systems: edit...] or again when sub-dialogs such as Create new class system or Change class system [Modify class system] <name> are closed.