alj87,
ICAO Annex 2 defines what a changeover point is:
Changeover point. The point at which an aircraft navigating
on an ATS route segment defined by reference to very high
frequency omnidirectional radio ranges is expected to transfer
its primary navigational reference from the facility
behind the aircraft to the next facility ahead of the aircraft.
Note.— Changeover points are established to provide the
optimum balance in respect of signal strength and quality
between facilities at all levels to be used and to ensure a common
source of azimuth guidance for all aircraft operating
along the same portion of a route segment.