Data Set Overview
    =================
      The Alpha-Particle X-Ray Spectrometer (APXS) is a contact
      instrument that uses X-ray spectroscopy to determine the
      elemental composition of soils and rocks. Atmosphere argon can
      also be measured by the APXS. The APXS is deployed on
      selected targets along the rover traverse to determine the
      elemental composition of samples. Materials processed by the
      Sample Acquisition - Sample Processing and Handling (SA/SPaH)
      system can also be delivered to the observation tray or to the
      martian surface for analysis by APXS. Elements heavier than Na
      can be detected by APXS. If present at sufficient levels, the
      abundances of these elements can also be determined.
 
      There are two APXS RDR data products. The first product is the summed
      X-ray spectrum in counts as a function of energy, which is
      derived from the APXS EDR. The second product is the standard elemental
      oxide abundance, which is derived from the summed X-ray spectrum.
      Both products are stored as ASCII text in a Comma Separated
      Value (CSV) format. Each CSV file has an associated detached PDS
      label, also stored as ASCII text.
 
    Processing
    ==========
      The APXS X-ray spectrum RDR products are considered CODMAC Level 4 or
      Resampled Data, equivalent to NASA level 1B. The spectra
      are generated from the APXS EDR products (CODMAC Level 2, NASA Level 0)
      archived in the PDS data set MSL-M-APXS-2-EDR-V1.0.
 
      The summed X-ray spectrum, product type RSP, is generated from the APXS
      EDR product by converting channel number to energy and summing
      together all buffers acquired at good temperatures. The RSP product
      consists of two fields, the first of which contains an energy value
      in eV and the second contains total counts for that energy channel.
      The count field value for first record is the counting time in
      seconds. The value for the last record is the overflow, that is,
      counts observed at that energy and higher. There is a header record
      at the start of the file that gives field headings for the two
      fields.
 
      The APXS oxide abundance RDR products are considered CODMAC Level 5 or
      Derived Data, equivalent to NASA Level 2. The oxide abundance products,
      product type RWP, are generated from the X-ray spectra.
 
      The oxide abundance product contains abundance data for
      a set of standard oxides and elements. There are three fields in the
      product: the oxide or element name, the weight percent, and the
      standard error of the weight percent value. The first record in the
      file is a header record that provides a description
      of the target sample.
 
 
    Software
    ========
      APXS RDR products are ASCII comma-delimited files that can be
      read using a text editor or with spreadsheet software such as
      Excel.  No special software is required.

Confidence Level Overview
    =========================
      See CAMPBELLETAL2012 for a description of the calibration
      applied to the APXS data.
 
    Review
    ======
      The APXS RDR products are reviewed internally by the APXS team
      prior to release to the PDS. PDS also performs an external peer
      review of the APXS RDR.
 
    Data Coverage and Quality
    =========================
      Nominally one APXS RDR spectrum is generated for each APXS EDR data
      product, and one APXS RDR oxide abundance product is generated for
      each RDR spectrum. Both the EDR and the RDR products may be revised
      during the course of the mission. Revisions are indicated in the
      product's PDS label by the keywords PRODUCT_VERSION_ID and
      PRODUCT_CREATION_TIME, and in the ERRATA.TXT file that accompanies
      the APXS archive.
 
    Limitations
    ===========
      N/A
 
    Data Compression
    ===============
      No data compression is used.