The 3xP3 entry in FlyBase represents an artificial promoter element that contains three tandem copies of the 'P3' sequence (TAAT(C/T)N(G/A)ATTA), an artificial, ideal binding site for Paired-type homeodomain dimers (PMID:7901121), fused upstream of a basal promoter element (FBrf0132292). 3xP3 drives expression in all photoreceptors in D.melanogaster (FBrf0093719) and in a number of other drosophilid (FBrf0212311) and insect species (reviewed in FBrf0155843).