The fourth character describes the peak type. It is shown only for forced integration events, or if manual integration has been triggered. For example, you use an integration event to define a solvent peak, or you use manual integration to correct the baseline or to delete a peak.
The peak is a solvent peak.
The peak is a negative peak.
The peak is an area summed peak.
Tangent-skimmed peak (standard skim, straight).
Tangent-skimmed peak (old mode exponential skim).
Tangent-skimmed peak (new mode exponential skim).
Tangent-skimmed peak or shoulder (gaussian).
Peak defined by manual baseline.
Negative peak defined by manual baseline.
Tangent-skimmed peak defined by manual baseline.
Tangent-skimmed peak (exponential skim) defined by manual baseline.
The peak is a recalculated peak.
Peak defined by a front shoulder tangent.
Peak defined by a rear shoulder tangent.
Peak defined by a front shoulder drop-line.
Peak defined by a rear shoulder drop-line.
The peak is unassigned.