In contrast to the first metric, the PRF scores are calculated based on the sums of TP, TN, FP and FN for all instances in the test dataset; we further consider whether the boundary matches that of the linked KB entry's mention.
under this criterion, an FP could link a true entity to the wrong KB entry or link a false entity to any KB entry; while an FN could link a true entity to the wrong KB entry or fail to recognize a true entity.