Figure 1: An example of cross-annotation in the aligned reads. (A) The true number of reads to each of the four COG families in the metagenome. (B) For each COG, only a partial number of the true reads being correctly assigned to the same COG. (C) In the alignment output, the read count to a COG includes the number of correctly assigned reads (from the same COG), and the number of erroneously assigned reads (from other COGs).