Note 262 — Chapter IX · CASTLES OF THE THIRTEENTH CENTURY: THE FORTIFICATION OF THE CURTAIN
Reading edition
Viollet-le-Duc, La Cité de Carcassonne, p. 27, has a drawing of a similar device with an upper and lower shutter (245): the upper shutter is propped open by iron guards: while the lower is hung in iron hooks fixed in the face of the wall.