The FlyBase record for P-element insertion line EY20997 (FBti0076413 P{EPgy2}Cp190EY20997) currently has a single flanking sequence entry, GenBank accession DX977691, and a sequence location of  3R:15 ,274,770..15,274,776 + (release 6). The GenBank accession sequence DX977691 is the 3’ flank. Please add the GenBank accession sequence DX977692 as the 5’ flank. The two flanks derived from inverse PCR align to opposite stands at exactly the same nucleotide site. During the course of the transposon mutagenesis studies of the Gene Disruption Project, such cases of the inverse PCR flanks aligning to the same site on opposite strands have been observed for a small minority of other P-element, piggyBac and Minos insertions (because of the 8 bp target site duplication that P-elements create when they insert and the convention we use to adjust for this duplication, the insertion site locations listed in FlyBase for these are generally 7 bp apart for P-elements). We infer that these are complex insertion events, but do not understand the structure of the inserted element(s) or in which orientation the insertion occurred relative to the reference genome.