X_INIT(1gmt)						       Generic Mapping Tools						      X_INIT(1gmt)

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  com-
	      plete 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.

GMT 4.5.7							    15 Jul 2011 						      X_INIT(1gmt)