A XEC (YEC, ZEC) is an infinite elliptical cylinder parallel to the x (y, z) axis, and with the axes of the ellipse parallel to the other two coordinate axes. Each XEC (YEC, ZEC) is defined by 4 numbers: A_y, A_z (A_z, A_x for YEC, A_x, A_y for ZEC) (coordinates of the cylinder axis), L_y, L_z (L_z, L_x for YEC, L_x, L_y for ZEC) (semiaxes of the ellipse). A XEC (YEC, ZEC) definition extends over one single card in default fixed format, and over two cards in high-accuracy body fixed format. Example in default fixed format:*...+....1....+....2....+....3....+....4....+....5....+....6....+....7..ZEC 101 15.0 319.0 33.0 80.0* (an infinite elliptical cylinder, centreed on x=15, y=319, with the* ellipse minor semi-axis parallel to x, 33 cm long, and the major* semi-axis parallel to y, 80 cm long)The same example in high-accuracy body fixed format:*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+.ZEC 101 15.0 319.0 33.0 80.0 The same body, described in free format: ZEC ChimneyA 15.0 319.0 33.0 80.0