NB: Look to tube shape not opening shape.
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.
Carcass: Part of wall on intervallum side.
OW: Outer wall.
SW: Single wall.
Carcass perforations: outer wall or single wall (OW/SW) | |_ Shape of carcass canals (OW/SW)