Step[@name='Step01']/Constraints/rigid_body[@mat='1']/prescribed[@bc='Rx'] factor 1.0,0.25:0.25:0.75 Material/material[@name='tibia']/center_of_mass relative (-0.1:0.1:0.1,-0.1,-0.1),(0.0,0.0,0.0),(-0.1,-0.1,-0.1) Discrete/spring/E factor 0.5