Hydrogenic model and Hartree-Slater model give good results for evaluating the K-shell excitation cross-section. A comparison of K-edge and cross-section profiles for low atomic number (Z) elements  shows that the cross-section profiles present the K-edge roughly for an edge where the fine structures are important, e.g. for boron nitride (BN).
Figure 3414a (a) shows a HAADF-STEM image of single-layered h-BN (hexagonal boron-nitride) and Figure 3414a (b) is a corresponding atomic model where a EELS linescan has been recorded, shown in (c) and (d). The STEM contrast of the N and B locations is determined by the atomic number, called Z-contrast. Figure 3414a (c) and (d) shows the EELS profiles of the boron K-edge and nitrogen K-edge signals, respectively. The N K-edge intensity does not go down to zero even between two nitrogen atoms because of EELS signal delocalization . The large probe tail and mechanical instabilities such as the specimen drift during the line scan may also partially contribute to the nonzero intensity but this should not be a dominant effect because the simultaneously recorded STEM profile clearly shows well-separated atoms similar to the STEM signal presented in Figure 3414a (a).
Figure 3414a. (a) A HAADF-STEM image of single-layered h-BN (hexagonal boron-nitride), (b) A corresponding atomic model where an EELS linescan was recorded (red: nitrogen, blue: boron), and (c) and (d) the EELS profiles of the boron K-edge and nitrogen K-edge signals. Adapted from 
Figure 3414b shows a boron monovacancy [4, 5] (indicated by the darkest contrast in (a)), in single-layered h-BN (hexagonal boron-nitride), induced by the knock-on effect.
Figure 3414b. (a) A boron monovacancy shown by the darkest contrast in the HAADF-STEM image of single-layered h-BN and (b) A corresponding atomic model (red: nitrogen, blue: boron). Adapted from 
EEL spectrum shown in Figure 3414c was obtained from BN nanotubes prepared by continuous laser ablation of BN targets. It presents
five different edges, including B, C, Ca, N and O.
|Figure 3414c. EEL spectrum obtained from BN nanotubes prepared by continuous laser ablation of BN targets. 
 Ahn C. and Rez P., Ultramicroscopy 17 (1985) 105.
 D. A. Muller and J. Silcox, Ultramicroscopy 59, 195 (1995).
 Kazu Suenaga, Haruka Kobayashi, and Masanori Koshino, Core-Level Spectroscopy of Point Defects in Single Layer h-BN, Physical Review Letters, 108, 075501 (2012).
 C. Jin et al., Phys. Rev. Lett. 102, 195505 (2009).
 J. Meyer et al., Nano Lett. 9, 2683 (2009).
 Nan Yao, Zhong Lin Wang, Handbook of Microscopy for Nanotechnology, 2005.