The primary reason why a rectangular frame surrounds most bookcases is so that the individual ledges can be spaced out at fixed intervals and supported evenly the whole way up. Interestingly, the Bibliotheque CO2 has this four-sided structure, yet it is not employed to its full stabilizing potential.
Designer Marine Gaveau decided that no panel would extend from right to left, connecting to both sides of the frame. Instead, each would be slipped into a slot on one side of the storage system and left to protrude stiffly and horizontally my means of its cantilevered anchorage. The bookshelf set comes with a collection of ledges of different lengths that can be arranged however one wishes. The oak Bibliothèque CO2 can thus better accommodate a wide variety of objects in a range of different spaces.