===========
                             LEVEL2 data
				          *
                              (R-3.00)
                             ===========

LEVEL2 nt-uple structure:

 ******************************************************************
 * Ntuple ID = 22     Entries = 2390      LEVEL2
 ******************************************************************
 * Var numb * Type * Packing *    Range     *  Block   *  Name    *
 ******************************************************************
 *      1   * L*4  *    1    *              * GENERAL  * GOOD2
 *      2   * I*4  *         *              * GENERAL  * NEV2
 *      3   * I*4  *         *              * GENERAL  * WHIC_CALIB
 *      4   * I*4  *         *              * GENERAL  * SWCODE
 *      5   * L*4  *    1    *              * GENERAL  * CRC(12)
 *      1   * U*4  *    6    * [0,50]       * CPU      * PKT_TYPE
 *      2   * I*4  *         *              * CPU      * PKT_NUM
 *      3   * I*4  *         *              * CPU      * OBT
 *      4   * L*4  *    1    *              * CPU      * CPU_CRC
 *      1   * I*4  *         * [0,50]       * TRACKS   * NTRK
 *      2   * U*4  *    6    * [0,50]       * TRACKS   * IMAGE(NTRK)
 *      3   * R*4  *         *              * TRACKS   * XM(6,NTRK)
 *      4   * R*4  *         *              * TRACKS   * YM(6,NTRK)
 *      5   * R*4  *         *              * TRACKS   * ZM(6,NTRK)
 *      6   * R*4  *         *              * TRACKS   * RESX(6,NTRK)
 *      7   * R*4  *         *              * TRACKS   * RESY(6,NTRK)
 *      8   * R*4  *         *              * TRACKS   * AL(5,NTRK)
 *      9   * R*4  *         *              * TRACKS   * COVAL(5,5,NTRK)
 *     10   * R*4  *         *              * TRACKS   * CHI2(NTRK)
 *     11   * U*4  *    1    * [0,1]        * TRACKS   * XGOOD(6,NTRK)
 *     12   * U*4  *    1    * [0,1]        * TRACKS   * YGOOD(6,NTRK)
 *     13   * R*4  *         *              * TRACKS   * XV(6,NTRK)
 *     14   * R*4  *         *              * TRACKS   * YV(6,NTRK)
 *     15   * R*4  *         *              * TRACKS   * ZV(6,NTRK)
 *     16   * R*4  *         *              * TRACKS   * AXV(6,NTRK)
 *     17   * R*4  *         *              * TRACKS   * AYV(6,NTRK)
 *     18   * R*4  *         *              * TRACKS   * DEDX_X(6,NTRK)
 *     19   * R*4  *         *              * TRACKS   * DEDX_Y(6,NTRK)
 *     20   * R*4  *         *              * TRACKS   * BdL(NTRK)
 *      1   * I*4  *         * [0,500]      * SINGLETX * NCLSX
 *      2   * I*4  *         *              * SINGLETX * PLANEX(NCLSX)
 *      3   * R*4  *         *              * SINGLETX * XS(2,NCLSX)
 *      4   * R*4  *         *              * SINGLETX * SGNLXS(NCLSX)
 *      1   * I*4  *         * [0,500]      * SINGLETY * NCLSY
 *      2   * I*4  *         *              * SINGLETY * PLANEY(NCLSY)
 *      3   * R*4  *         *              * SINGLETY * YS(2,NCLSY)
 *      4   * R*4  *         *              * SINGLETY * SGNLYS(NCLSY)
 ******************************************************************
 *  Block   *  Entries  * Unpacked * Packed *   Packing Factor    *
 ******************************************************************
 * GENERAL  *  2390     * 64       * 14     *       4.571         *
 * CPU      *  2390     * 16       * 9      *       1.778         *
 * TRACKS   *  2390     * 23404    * Var.   *    Variable         *
 * SINGLETX *  2390     * 8004     * Var.   *    Variable         *
 * SINGLETY *  2390     * 8004     * Var.   *    Variable         *
 * Total    *    ---    * 39492    * Var.   *    Variable         *
 ******************************************************************
 * Blocks = 5            Variables = 37      Max. Columns = 9873  *
 ******************************************************************

The GENERAL block stores the global event flag GOOD2, the event counter NEV2, 
a variable that relates each event to the calibration parameters (WHICH_CALIB)
the version number of the software (SWCODE) and the result of the crc check for
the 12 views of th etracking system (CRC(12)).
If WHICH_CALIB=0 (missing calibration) then GOOD2=.FALSE.

The CPU block stores the event tag extracted from the physics-packet 
CPU-header (PKT_TYPE, PKT_NUM, OBT, CPU_CRC) . 

The TRACKS block stores track information: 
  NTRK           - number of identified tracks (in case the Y ambiguity is not
                   solved both the track images are stored)
  IMAGE(NTRK)    - ID of the track image (=0 if no image)
  XM(6,NTRK)     - measured coordinates associated to the track
  YM(6,NTRK)       '
  ZM(6,NTRK)       '
  RESX(6,NTRK)   - spatial resolution associated to each coordinate
  RESY(6,NTRK)     '
  AL(5,NTRK)     - TRACK PARAMETERS: X0,Y0,sin(THETA0),PHI0,DEFLECTION 
  COVAL(5,5,NTRK)- Variance/covariance matrix of parameters
  CHI2(NTRK)     - reduced chi^2 of the track 
  XGOOD(6,NTRK)  - flag indicating if a plane was included in the track fitting
  YGOOD(6,NTRK)    '
  XV(6,NTRK)     - calculated coordinates
  YV(6,NTRK)       '
  ZV(6,NTRK)       '
  AXV(6,NTRK)    - calculated angles
  AYV(6,NTRK)      '
  DEDX_X(6,NTRK)  - energy release in MIP, scaled to 300 microns, for x clusters
  DEDX_Y(6,NTRK)  - energy release in MIP, scaled to 300 microns, for y clusters
  BdL(NTRK)       - integral, along the track, of BxdL (T*m))
  
The SINGLETS block stores information about those clusters not associated with 
any track: 
  NCLSX          - number of singlets on the x views 
  PLANEX(NCLSX)  - plane which the i-th x-singlet belong to
  XS(2,NCLSX)    - coordinate (on sensors 1 and 2)
  SGNLXS(NCLSX)  - signal in MIP (not scaled)
  NCLSY          - number of singlets on the y views 
  PLANEY(NCLSY)  - plane which the i-th y-singlet belong to
  YS(2,NCLSY)    - coordinate (on sensors 1 and 2)
  SGNLYS(NCLSY)  - signal in MIP (not scaled)