Three of the aesthetic knots (the St Andrew, Cavendish, and Grantchester) have the same symmetry and balance values as at least one other knot in their class; in this case, they appear to have been selected based on how evenly they distribute the unbalanced portions throughout the knot. This can be readily seen when one views these knots as combinations of two smaller knots, as the balance values of each component add up to the balance value of the final knot. In unbalanced knots where the balance value is odd, it is broken up so that the more unbalanced portion of the two is placed towards the beginning of the knot. This is probably intended to help the outermost portion of the knot keep its shape and remain tight.