has_metric_category has relation has_units has_value_concept has value type n-tuple ID free metric single run based metric MS metric imaging metric reference m/z error image reference m/z error image quantiles MS MS:4000233 A compact summary of the reference m/z error image (MS:4000232). A shift of the central quantiles away from zero indicates a systematic calibration offset, whereas a widening spread indicates drift or instability over the acquisition. Not acquired positions and positions in which the reference ion was not detected are excluded from the calculation. The first to n-th quantile of the reference m/z error values over all spectra of an imaging acquisition in which the mass reference ion was detected. A value triplet represents the quartiles Q1, Q2, Q3. The number of values in the tuple implies the quantile mode. QC reference m/z parts per million