The affine symmetry e⁷11 induces natural transformations of all three forms:

In the case of the Power type Form PiMod₁₂Set one has two natural choices to define @e⁷11_Set – namely to choose either the image or the pre-image of a set under @e⁷11, but in this case both coincide because e⁷11 is self-inverse. The same graph with two nodes and one arrow can be loaded in three other ways, namely each time with one of the three compound Forms at both nodes and the corresponding natural transformation at its

arrow. The resulting diagrams are called:

Defining the following Limit-Forms – having these Diagrams as their Coordinators – enables us to discuss Harrison’s dual network of harmonic concepts and express it in terms of suitable Denotators.

1. Modal Duality: Major / Minor. The initial inversion e⁷11 has been chosen in such a way that the underlying diatonic scales of C-Major and C-Minor are exchanged. This is expressed in terms of the PiMod₁₂DualSets-Denotator “DualScales”:
2. Agents Discharge: 7-8 / 6-5: The typical leading tone-motion 7-8 is characterized in Harrison’s system as a discharge of the Dominant agent into the