#extension_course__extensioncourse  a course offered as part of an extension service
  supertype:  course__course_of_instruction__course_of_study__class__clas  education imparted in a series of lessons or class meetings; "he took a course in basket weaving"; "flirting is not unknown in college classes"
  part of:  university_extension__extension__extension_service__extensionservice  an educational opportunity provided by colleges and universities to people who not enrolled as regular students

No statement uses or specializes extension_course; click here to add one.