The Mi{PT-BM.un} entry in FlyBase is used to denote the transgenic construct present in an insertion when it is known that the inserted element corresponds to one of Mi{PT-BM.0}, Mi{PT-BM.1} or Mi{PT-BM.2}, but it is not known which of these 3 intron phase variants the inserted element corresponds to. The Mi{PT-BM.un} element is generated in vivo by using phiC31:int-mediated recombination to replace the attP cassette of a Mi{MIC} element insertion with a protein trap cassette composed of a splice acceptor site, a (GGS)[[4]] flexible linker, a multiple tag cassette (EBFP2 - 3xTag:MYC), another (GGS)[[4]] flexible linker and a splice donor site.