This column shows the Affymetrix ID from the U74 series of chips (a, b, and c) that best corresponds to each gene.
Target genome sequences were downloaded from the Affymetrix Product Support and mapped to the genome using blat followed by pslReps with the parameters -minCover=0.3 -minAli=0.95 -nearTop=0.005. For each gene, the target with the most overlap (on the same strand and excluding introns) was selected.