Raw data, corresponding to individual dumps of the correlator buffers, are not stored. Instead, a real-time job applies automatic calibrations (clipping corrections, atmospheric model, etc.) before writing on disk. This pre-calibrated data is archived daily, and sorted on a project by project basis.
Except for specific experiments, PIs will only have access to the sorted data, which contain the source data and all the calibration measurements acquired by the observing procedure. PIs will have exclusive access to their data for a three year proprietary period (counting from the end of the last semester of observations of the project), but no exclusive rights over the calibration data, which are duplicated in special data files to monitor a posteriori the performance of the interferometer.
Off-line calibration (RF bandpass, phase, flux, and secondary amplitude calibration) is the PI's responsibility. It is possible to recalibrate the data for atmospheric transmission and receiver temperature. Recalibrating the IF bandpass is not possible.