I assume these notes are for EJB3.0. I have seen many posts where the users are confused with similar statements in EJB3.
Starting EJB3, there is now a concept of "business interface", which is a Plain Old Java Interface. So a business interface MUST NOT extend the javax.ejb.EJBObject or javax.ejb.EJBLocalObject interface.
On the other hand EJB3 is backward compatible. What this means is, you can have EJB2.x style beans in your EJB3 application. The "Remote interface" is specifically meant for these EJB2.x beans. So a "Remote Interface" (implies this is for a EJB2.x bean) will be extending from the javax.ejb.EJBObject.