Each Fontana has a "source" from which the shapes radially emerge, similar to a Fountain (for which Fontana is named).
When the Composition is Adjacent, there are two sources opposing each other in the piece, creating a rift where their radial elements meet.
With the Single Composition, a single source centralized to the piece emerges.
The Free Composition results in any possibility, and the source is often not central to the piece.
The Cascade composition has 3 sources that overlap and create brilliantly busy outputs.