Validation of gene models. A , At a false discovery rate of 10%, ~64% of all exons on chromosome Ib are called "Present" (see Materials & Methods for details). B , These P/A calls are highly non-random in their distribution, with multi-exon genes showing good consistency among their individual exon calls (i.e. the majority of genes show expression of most annotated exons, or no expression at all). C , Among genes with inconsistent P/A calls, expression patterns are often clustered, suggesting alternative gene models. For example, the expression patterns associated with the kinesin motor domain-containing protein (25.m01768) suggest a coding start site that begins with the eighth exon.