NB: Convention: Tube begins on intervallum side.
Canal: Pore modified by skeletal structure thikening or by lintels streching. Canal length is greater than perforation diameter.
Lintel: Skeletal structure separating and bounding adjacent pores/canals.
Carcass: Part of wall on intervallum side.
OW: Outer wall.
SW: Single wall.
Downwardly opening: Opening on intervallum side is higher than the other one.
Some canals tubes have a horizontal opening, others have an upwardly opening.
Upwardly opening: Opening on intervallum side is lower down than the other one.
Horizontal opening: Opening on intervallum side is as high as the other one.
Type of carcass perforations: outer wall or single wall (OW/SW) | |_ Direction of carcass canals tubes (OW/SW)