Sourced cluster intervals retain the database or publication from which their coordinates were imported. PICB-detected intervals retain their sequencing accessions separately from the PICB method citation. Sourced-interval coverage is the fraction of a PICB interval covered by the union of sourced intervals. The website displays only PICB-detected intervals that pass the post-PICB matched random-placement accepted-piRNA-locus enrichment threshold at FDR ≤0.05. This is a website display and reporting threshold, not a PICB caller-level FDR. proTRAC comparisons use the method described by Rosenkranz and Zischler 2012.