NAME

       x_init - Initialization of Cross-Over Data Bases.

SYNOPSIS

       x_init -I

DESCRIPTION

       The  purpose  of x_init is to create two key files that will be holding all the cross-over
       information for all the cruises tested. These files are called  xx_base.b  and  xx_legs.b,
       and  they  will  contain  data  for each cross-over and totals for each leg, respectively.
       x_init will create these two files in the current directory, and write out the  fileheader
       with  a  1 as the next record number in the case of xx_base.b. NB! Any previous files with
       the same names in the current directory will be erased, so use with caution.

       -I     Must be present form initialization to take effect.

BEWARE

       Both files are binary and have fixed record lengths. The  formats  of  the  files  are  as
       follows:

       xx_base.b:
                   Record length = 40 bytes.
                   Rec # 1:       fileheader
                   Rec # 2:       pairheader
                   Next n recs:        crossover-structure
                   Rec  #  n+3:        pairheader etc.
              The  fileheader  is a 40 byte character string where the last 10 bytes contains the
              record number of the last record  in  the  file.   The  pairheader  is  a  40  byte
              character  string  which  contains  the  names  of the two legs in question and the
              number of COEs generated between them.  The crossover-structure  contains  all  the
              information  for  one  COE,  that  is  lat,  lon, time along leg values of gravity,
              magnetics, and bathymetry at the cross-over point, the heading of track #1, and the
              heading  of  track #2. See program listing for more details on formats. The file is
              sequential in that new data are appended at the end of the file.

       xx_legs.b:
                   Record length = 204 bytes.

              Each record contains the complete information for each leg that has  been  checked.
              The  leg-structure contains fields like year of cruise, number of internal/external
              COEs for gravity, magnetics, and bathymetry, their means and  standard  deviations,
              and the best fitting regression lines, i.e., the dc-shifts and drift-rates computed
              from the time/error data points. See program listing for  complete  description  of
              record format.

SEE ALSO

       GMT(1), x_system(1)

REFERENCES

       Wessel, P. XOVER: A Cross-over Error Detector for Track Data, Computers & Geosciences, 15,
       333-346.