+/**
+ * A member of an equivalence class of geometric objects whose
+ * positions are related by affine transformation matrices and are
+ * constrained by an affine constraint.
+ *
+ * Every HasBindingGroup (henceforth, HBG) begins life as a member of
+ * a singleton binding group consisting only of itself.
+ *
+ * Invoking bindTo() upon a pair of HBG's that are not part of the
+ * same BindingGroup will merge the two BG's. Invoking bindTo() upon
+ * a pair of HBG's that are already part of the same BG will result
+ * in the imposition of an AffineConstraint on the BG.
+ */