Vertical intervallar structures: Longitudinal and often radial structures inside the intervallum (septa, taeniae...).
Intervallum: Space enclosed between the walls.
Presence of vertical intervallar structures | |_ Porosity of vertical intervallar structures | |_ Repartition of vertical intervallar structures pores {Aporous , One row of pores per vertical structure} | |_ Porosity type of vertical intervallar structures {Aporous , One row of pores per vertical structure} | |_ Pores shape of vertical intervallar structures {Aporous}