épaisseurcontains a measurement measured across the
spine of a book or codex, or (for other text-bearing objects) perpendicular to the measurement given by the
width element.책의 등(두께) 치수를 명시한다.橫跨書脊的測量值。冊子の背と平行した深さを示す．contient une dimension mesurée sur le dos du
manuscrit.refiere la medida tomada del ancho del dorso.***si riferisce a una misurazione presa lungo la larghezza del dorso64
If used to specify the width of a non text-bearing
portion of some object, for example a monument, this element
conventionally refers to the axis
facing the observer, and perpendicular to that indicated by the
width axis.