The schematic planar view of a 8-β -strand barrel (strand 1 is duplicated for clarity). Thick lines represent the peptide bonds between consecutive amino acids along their strand. Thin lines represent the hydrogen bonds between the amino acids in adjacent strands. In this example, the shear number is S = 10, which is the ordinal distance between amino acids A and B. We note that all known β -barrels have a positive shear number  and are slanted "to the right", as illustrated here.
Tran et al. BMC Genomics 2012 13(Suppl 2):S5 doi:10.1186/1471-2164-13-S2-S5