NAME

       x_list - Extract Cross-Over Information from the Data Base.

SYNOPSIS

       x_list  [  leg1 ] [ leg2 ] [ -dataflags ] [ -Rwest/east/south/north ] [ -Xxbase ] [ -H ] [
       -I ] [ -V ] [ -Ccorrfile ] [ -Zignorefile ]

DESCRIPTION

       x_list will allow the user to extract information from the xx_base.b and xx_legs.b  files.
       Several  options can be passed on the command line in order to specify which parameters to
       extract. They are:

       leg1 leg2
              If two legs are specified, the cross-overs they have in common  are  returned.   If
              one leg is specified, all the external cross-overs involving this leg are returned,
              OR only its internal cross-overs if -I is selected.  If no legs are given, all  the
              external (or internal with -I) cross-overs are returned.  This program is useful if
              one wants to look at, say, gravity COEs versus time from port for a particular leg,
              etc.

       dataflags
              This is a string of any combination of the following:
                   l means list both legnames.
                   t means list time.
                   x means list longitude.
                   y means list latitude.
                   g means list gravity COEs.
                   m means list magnetics COEs.
                   b means list bathymetry COEs.
                   G means list average gravity at cross-over.
                   M means list average magnetic anomaly at cross-over.
                   B means list average bathymetry at cross-over.
                   h means list heading of ship at cross-over.
              The  components  are written out in the order they appear in dataflags. The default
              output is -txygmbGMBhl.  When internal COEs are desired, the time reported  is  the
              elapsed  time since the ship first occupied the cross-over point. For external COEs
              the time means time from the start of the year in seconds.

       -R     Only return cross-overs inside the specified region west, east, south,  and  north.
              [Default is world].

       -X     Indicate alternate xx_base.b file.

       -H     Issue one header record on output.

       -I     Report on internal COEs [Default is external COEs].

       -C     Apply  cross-over  correction to the data (i.e., reports the cross-over value after
              the best-fitting corrections have been applied to both legs).  If  no  corrfile  is
              given, the default correction file is assumed.

       -Z     Ignore those legs that appear in the ignorefile.

       -V     Selects  verbose  mode,  which  will  send progress reports to stderr [Default runs
              "silently"].

SEE ALSO

       GMT(1), x_system(1)

REFERENCES

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