## 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.

## 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, magnet
                  ics, 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(l), x_system(l)

## REFERENCES

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

                               15 Oct 2001                  x_init(l)