A <VenueOverride> element occurs inside an <Extension> if the performances contained in the sibling <ScheduleExtension> are taking place in a different <Venue> (even if it is only the inner <PerformanceSpace> that is changing) to the one defined for the <Event>. If the <VenueOverride> is not defined then the performances will take place in the <Venue>.
Attributes
Anything that <Venue> permits (1.1.6)
Contained Within
Anything that <Venue> permits (1.1.6)