Roles and permissions

Yes, I already discovered how I, as a teacher, can override permissions for an existing role (e.g., Student) in a course context. What led me to believe that I could also define my own roles in course is the wording of the capability "Define and manage roles."

I think you can allow your teachers to create roles at the global level

In the experiment I described earlier [in which the admin added the permission "Define and manage roles" to Teacher and then assigned the global role Teacher to me in the Core System context], I (as Teacher) was not able to define roles at the global level.

So then, I guess the only way for a Teacher to alter permissions within a course is to through the "Override permissions for others" capability. Given permission, the teacher can then apply overrides to Student, non-editing teacher, or guest, or any other role that has been checked (by the admin) in the "Allow roles override" table. The "Define and manage roles" capability is irrelevant to teachers.

Is this true?