This diagram is supposed to show the truncation relations between a regular polyhedron or tiling {p,q}, its dual, {q,p}. You'll see there's two truncated forms, one for parent, one for dual, and three "middle" forms which are common to both.

Example:

• Parent: t₀(4,3}
• Truncated parent: t_0,1(4,3}
• Rectified (either): t₁(4,3} = t₁(3,4}
• Truncated dual: t_0,1(3,4}
• Dual: t₀(3,4}
• Runcinated (either): t_0,2(4,3} = t_0,2(3,4}
• Onmitruncated (either): t_0,1,2(4,3} = t_0,1,2(3,4}
• Not in diagram: snub (either): s(4,3} = s(3,4}