Gives back the spatial relationship operators given 2 ribbons(ie squares) There are a total of 169 different relationships that can exist between 2 squares each relationship can be encoded as a sequence of 4 characters, 2 chars for the operators and 2 chars for the symmetry indicator, since most(all except equals) have a mirror symmetric version.
https://people.cs.pitt.edu/~chang/365/chap4.htm
These 169 relationships can be placed into 5 categories
1.Disjoint 2.Joint 3.Partial Overlap 4.Contained 5.Belonging
These can be categorized easily with the relationship string Lee and Hsu came up with. The strings only need to be checked for 5 rules plus a default in order to properly categorize the squares.