GML 3.1.0 - Confusion about feature properties

I am working on a GML Application Schema. A lot of what I have read has said that features can have feature properties, but I seem to have run into some contradictions to this in the 3.1.0 GML draft spec (OGC 03-105r1).

Page 21 - "The value of a property may be simple, or it may be a feature or other complex object."

Page 23 - "No GML object may appear as the immediate child of a GML object."

Page 259 - "All geographic features and feature collections in the application schema shall be declared as global elements in the schema, i.e. they shall be immediate child elements of the XML Schema element."

Can I have a global element of a complexType extended from the gml:AbstractFeatureType that adds other types derived from AbstractFeatureType as properties?

Any clarification, especially valid XSD samples, would be greatly appreciated.