The analysis of near edge structure on inner shell ionisation edges in electron energy loss spectroscopy (EELS) can lead to new insights on the nature of bonding on an atomic scale. To fully understand the origins of spectral features it is necessary to calculate the near edge structure from a suitable theoretical model . Many of the previously published theories are based on multiple scattering of the ejected electron in a cluster of atoms surrounding the site of the excitation. The techniques used for the selection of scattering paths account for most of the differences between the various theories. In the XANES method the atoms in the vicinity of the excited atom are assigned to coordination shells and a separation is made between scattering within a given shell (intrashell) and scattering between shells (intershell). The FEFF method selects paths up to a given maximum length according to the number of scatterings and estimated amplitude.