FlyBase curator comment: The P{?'} entry in FlyBase is used to denote the partial transposon present in an insertion when it is known that the inserted sequence is a deleted version of the P-element natural transposon (generated during transposition/excision), and where it is known that the deletion removes one end of the P-element, but it is not known which transposable-element end has been removed. For details of what portion of the original P-element remains for an individual insertion of P{?'}, see the description in the insertion report and/or in any allele reports associated with that insertion.