FlyBase curator comment: The P{5'lacZ} entry in FlyBase is used to denote the transgenic construct present in an insertion when it is known that the inserted element is a deleted version of P{lacZ} (generated during transposition/excision), and where it is known that sequences have been deleted from the 3' end of the P{lacZ} element (this includes cases where a single 5' terminal repeat is all that remains). For details of what portion of the original P{lacZ} element remains for an individual insertion of P{5'lacZ}, see the description in the insertion report and/or in any allele reports associated with that insertion.