4. A system according to claim 1 , further comprising: a further compass provided within the two-dimensional display.
5. A system according to claim 4 , further comprising: a label determination module to determine the spine labels for the compass and the further compass by generating a set of spine labels for the cluster spines that appear within one of the compasses that is concentric to the other compass and by generating a different set of spine labels for those cluster spines that appear only within the other compass.