On the hand-scored profiles, why do the interval marks on the left and right sides of the profiles correspond to T score intervals but not to percentile intervals?

The Manuals for the ASEBA forms explain how normalized T scores were assigned to “midpoint percentiles” on the basis of percentiles computed from cumulative frequency distributions of raw scores in normative samples. Owing to the normalized nature of the T scores, the T scores do not have 1-to-1 relations to percentiles. Some T scores represent multiple percentiles. Consequently, it is not possible to represent the percentiles in terms of equal intervals like those displayed on the hand-scored profiles for T scores. If you want to know the specific percentiles for a particular raw scale score, use the ASEBA computer-scoring software, which displays the percentile for each raw scale score.