The first character describes the baseline at the start of the peak and the second character describes the baseline at the end of the peak.
The peak started or stopped on the baseline.
The peak started or stopped while the baseline was penetrated.
The peak started or stopped with a valley drop-line.
The peak started or stopped on a forced horizontal baseline.
The peak started or stopped on a forced point.
The peak was manually integrated.
The peak was unassigned.
Additional flags may also be appended (in order of precedence).