Data set Version 2.0
      ====================
      The ROSINA team found corrupted files in the RTOF and DFMS
      science data V1.0 of this dataset, these corrupted files have
      been removed in the V2.0. The list of these removed files can be
      found in the REMOVED_L3_V1_TO_V2.ASC file.
      Furthermore, the mass scale has been enhanced for a selection
      of masses which are now provided with 4 digits after the coma
      (MCP HR neutral spectra for masses 16, 17, 18, 27, 28, 30, 32,
      34, 44, 46, 60, and 76) and the offset removal has been
      improved. As a result, V2.0 of this CODMAC L3 dataset has been
      created.

      Some of the CODMAC L2 data with a DATA_QUALITY field set to 0
      have been post-processed and re-generated. When bytes of the
      science data stream were lost by the DPU, it is possible to
      rebuild the science data by analysing and correcting these
      anomalies. Another problem originates from the MCP detector
      readout process: an offset can suddenly be added to the data at
      any time during the readout; spectra with such an offset have
      also been corrected using some offset subtraction to cancel this
      effect. The re-generated PDS files with their original
      DATA_QUALITY flag are provided in the software zip file
      containing all the input files used by the software to convert
      the L2 data into L3 data.

      Data set Overview
      =================
      Rosetta was at distances between 80 and 220 km from the comet
      during this time, except during a close flyby on March 28, 2015.
      ROSINA was permanently analysing the coma of the comet with DFMS
      and COPS sensors and the RTOF sensor part of the time
      (instrument performance permitting), except during wheel
      offloadings when the mass
      spectrometers DFMS and RTOF were in standby and during orbit
      control manoeuvers, when all sensors were off. Explanation
      on the data generation of the ROSINA sensors can be found in
      the OPERATION_LOGBOOK.ASC. COPS data  do not need on-ground
      calibration and are included in the level 2 dataset.

      Parameters
      ==========
      DFMS and RTOF data contain neutral gas data as well as ion data.
      The data are raw, uncalibrated data. COPS data contains nude
      gauge pressure values of the combined spacecraft and cometary
      signal.

      Calibration
      ===========
      The level 3 data products are calibrated with mass scale and
      intensity.
      The procedure required to calibrate the RTOF and DFMS data is
      described in our User manual, Annex D1 (DOCUMENT directory). The
      ROSINA Team defined quality flags for the data which will then
      tell the user how well the mass scale and the intensity scale
      have been defined.

      Processing
      ==========
      Processing the RTOF and DFMS CODMAC L2 PDS to L3 PDS calibrated
      data is detailed in the SOFT_RTOF_L2_TO_L3.PDF and
      SOFT_DFMS_L2_TO_L3.PDF documents. These documents also contain
      use and installation instructions of the software.

      Software
      ========
      Software to convert L2 to L3 data is provided. It produces the
      calibrated data from the L2 data. Another software is also
      provided to enhance the mass scale of the DFMS CODMAC L3
      products.

      Media/Format
      ============
      The standard distribution format for the data is an electronic
      volume.

      Coordinate System
      =================
      The geometry items SC_SUN_POSITION_VECTOR,
      SC_TARGET_POSITION_VECTOR and SC_TARGET_VELOCITY_VECTOR provided
      in the label of the data product are relative to the Earth Mean
      Equator and Equinox reference frame of J2000.
      SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE are given in
      the Cheops reference frame.
      The SPACECRAFT_ALTITUDE gives the distance to the spacecraft
      from the target center of mass. These parameters are computed at
      time t=START_TIME.
      Distances are given in km, angles in degrees.

      Cheops Reference Frame
      ======================
      Scholten, F., Preusker, F., Jorda, L, and Hviid, S.,
      Reference Frames and Mapping Schemes of Comet 67P/C-G,
      RO-C-MULTI-5-67P-SHAPE-V1.0:CHEOPS_REF_FRAME_V1,
      NASA Planetary Data System and ESA Planetary Science Archive,
      2015.

Confidence Level Overview
      =========================
      All data have been validated by the ROSINA team and found as
      expected. Any exceptions are noted by the DATA_QUALITY field in
      the label files.