SAGE tag classification and spatial distribution. In total 5,304 unique tags with a count ≥2 were attempted to be assigned to a UniGene (NCBI build #38) sequence. The tags were classified into 5 categories according to the sequence alignment (a); Perfect forward matches (yellow), Perfect reverse matches (black), fuzzy forward matches (red) and fuzzy reverse matches (blue), no match to a UniGene (green). Distribution analysis of the forward (b) and reverse (c) tags across the length of the transcript was performed on total tag count data for tags with an annotation and a count ≥2 and reveals that the majority of tags are derived from the 3' most CATG site (position 1) of the respective transcripts. The perfect matched tags (blue) follow the same pattern as the fuzzy matches (red).