ABSTRACT
A (combinatorial ordered Q)-configuration of seven points 1, . . . 7 will be encoded with the set of seven subcodes describing the subconfigurations 1ˆ, . . . 7ˆ. As for the case n = 6, we shall call line-walls (resp. conic-walls) the almost generic configurations with three aligned points (resp. six coconic points). Consider an ordered conic-wall, with 1, . . . 6 disposed in this ordering on the conic. The mutual cyclic orderings of 1, . . . , 6 given respectively by the conic and the pencil of lines based at 7 may be described with a conic-diagram: a closed polygonal line with six vertices, inscribed in a circle (where a vanishing triangle of the polygonal line is assimilated to a triple point). It is easily seen that there are exactly eleven admissible unmarked conic-diagrams.
