Description: {hkl}-triangular representation of the forms in the diploidal class. Names are in Spanish, but they are really similar to them in English. Vertex "h" matches the form {100} because h=1, k=0 and l=0. Vertex "k" matches {010} and "l" {001}. I have drawn some examples of positive and negative diploids. You can easily see why these forms are classified as 'invariant' (represented by single points), 'univariant' (represented by segments or lines with dim=1, you can move along the line and modify the aspect of the form) and 'divariants' (represented by areas, with dim=2, you can move with 2 degrees of freedom along the plane).

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