2-D plots for Figure 3 with different viewpoint specifications. The tetra-nucleotide usage patterns for the replicase open reading frame in each virus have been redisplayed on the (1st vs 2nd), (1st vs 3rd) and (2nd vs 3rd) eigen-vector axes ('o' represents positive strand ssRNA virus; 'x' represents negative strand ssRNA virus). For the top figure, the order for 'o' is [15,17,12,16,8,14,9,11,13,4,7,3,10,6,2,5,1]* (left to right), whereas 'x' is [24,27,25,28,22,26,18,23,20,19,21]* (left to right). For the middle figure, the order for 'o' is [15,17,12,16,8,14,9,11,13,4,7,3,10,6,2,5,1]* (left to right), whereas 'x' is [24,27,25,28,22,26,18,23,20,19,21]* (left to right). For the bottom figure, the order for 'o' is [15,17,12,16,8,14,9,11,13,4,7,3,10,6,2,5,1]* (left to right), whereas 'x' is [24,27,25,28,22,26,18,23,20,19,21]* (left to right). *The corresponded virus for each number follows Figure 3.