Difference in shock standoff distance between values calculated using the empirical relation for spherical objects (S) given in Seiff (1962) and the standoff distance as derived from observations (O) of the ICME structures sheath as well as sheath+LE (see symbols in the legend). For the Seiff relation we used different obstacle sizes, ME half-width (size as given in Fig. 4 divided by 2) and ME half-width plus the LE size (ME+LE). The dashed-dotted, solid and dashed lines give linear fits to the differences found for sheath/ME+LE, sheath/ME, and sheath+LE/ME.