You can click the class name on the Local Unit Schema page to open the Object Class Descriptor page:
This table lists the Class attributes - required and optional.
The first part of the table lists the attributes defined for the class itself, while the second part of the table lists the attributes defined in the class parent classes.
You can extend your Schema by adding more attributes to a Schema Class. Select the attribute name from the pop-up menu and click either the Add Required Attribute or Add Optional Attribute button.