Jan Dibbets), was documented with photographs and a film as well as a map of the city on which the geometric trace of the line is also recorded. Map, tracing on the map and marking of the territory enabled Pettena to intervene in the field of reality, without producing any additional objects. Close to the markings in Richard Lang’s landscape (Walking a Line in Peru, 1972), the lines drawn in the snow by Dennis Oppenheim (Time Line, 1968) and in the desert by Walter de Maria, Red Line establishes a new framework of perception, which follows the city limit, with nearby nature extending beyond. Between nature and architecture, city and country, the red line makes visible the borders that structure our mental field of perception. It changes ourMore than a dozen works by Group of Seven member A.Y. Jackson are being sold at auction this week, put on the block by the Art Gallery of Ontario.

But why would one of Canada's major art galleries ever get rid of artworks, let alone pieces by one of the country's best-known artists?

The practice is called deaccessioning — and it's not without controversy in the art world.

What is deaccessioning?

When a museum or gallery adds an object, it's called accessioning. The process involves a thorough analysis of everything to do with the piece, including its physical condition and legal ownership. Once that's done, the item is assigned a number and officially logged into the institution's permanent collection.

Think of deaccessioning as the reverse. It's when a cultural organization decides to cut