A method of mass spectrometry comprising: providing an orthogonal acceleration Time of Flight mass analyser comprising an orthogonal acceleration region; providing a first packet or group of parent or precursor ions; fragmenting said first packet or group of parent or precursor ions into a first plurality of fragment or daughter ions or allowing said first packet or group of parent or precursor ions to fragment into a first plurality of fragment or daughter ions; orthogonally accelerating at least some of said first plurality of fragment or daughter ions so that said at least some of said first plurality of fragment or daughter ions possess a first orthogonal energy; detecting fragment or daughter ions of said first plurality of fragment or daughter ions having said first orthogonal energy; generating first mass spectral data relating to fragment or daughter ions of said first plurality of fragment or daughter ions having said first orthogonal energy; providing a second packet or group of parent or precursor ions; fragmenting said second packet or group of parent or precursor ions into a second plurality of fragment or daughter ions or allowing said second packet or group of parent or precursor ions to fragment into a second plurality of fragment or daughter ions; orthogonally accelerating at least some of said second plurality of fragment or daughter ions so that said at least some of said second plurality of fragment or daughter ions possess a second different orthogonal energy; detecting fragment or daughter ions of said second plurality of fragment or daughter ions having said second orthogonal energy; generating second mass spectral data relating to said fragment or daughter ions of said second plurality of fragment or daughter ions having said second orthogonal energy; and forming a composite mass spectrum by using, combining or overlapping said first mass spectral data and said second mass spectral data. providing an orthogonal acceleration Time of Flight mass analyser comprising an orthogonal acceleration region; providing a first packet or group of parent or precursor ions; fragmenting said first packet or group of parent or precursor ions into a first plurality of fragment or daughter ions or allowing said first packet or group of parent or precursor ions to fragment into a first plurality of fragment or daughter ions; orthogonally accelerating at least some of said first plurality of fragment or daughter ions so that said at least some of said first plurality of fragment or daughter ions possess a first orthogonal energy; detecting fragment or daughter ions of said first plurality of fragment or daughter ions having said first orthogonal energy; generating first mass spectral data relating to fragment or daughter ions of said first plurality of fragment or daughter ions having said first orthogonal energy; providing a second packet or group of parent or precursor ions; fragmenting said second packet or group of parent or precursor ions into a second plurality of fragment or daughter ions or allowing said second packet or group of parent or precursor ions to fragment into a second plurality of fragment or daughter ions; orthogonally accelerating at least some of said second plurality of fragment or daughter ions so that said at least some of said second plurality of fragment or daughter ions possess a second different orthogonal energy; detecting fragment or daughter ions of said second plurality of fragment or daughter ions having said second orthogonal energy; generating second mass spectral data relating to said fragment or daughter ions of said second plurality of fragment or daughter ions having said second orthogonal energy; and forming a composite mass spectrum by using, combining or overlapping said first mass spectral data and said second mass spectral data.