Wandora

I find a triple association (album-track) inside ArtofNoise example. However I was not able to produce such association from the GUI. And I was not able to found schema for the album-track association.
The answer is "Add Player"

Thanks Mordenkainen

Indeed the user can create a triple association by pressing Add player button while in association editor.

To continue, the user can transform any binary association into a triple association by selecting menu option Insert player to associations. Menu option locates in the context menu that appears when user right mouse clicks an association in an association table. Association tables can be found in Traditional topic panels, for example.

Another convenient way of creating triple (and any other) associations is Sketch grid's Make associations tools:
http://www.wandora.org/wiki/Sketch_grid