identical unit or proportional unit of the body

time-rock unit =time-stratigraphic unit

arc stair

auxiliary stair

Cantilever Stair

circular stair

corkscrew stair

crane stair

double stair horizontal well

double stepping on one stair

Escape Stair

exterior stair

Fire Escape Stair

fire-escape stair

floor slab with stair steps

halfpace stair

main stair

newel stair

open newel stair