## 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  speci
                  fied,  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 follow
                  ing:
                          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 -txygm
                  bGMBhl. 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     Operate in verbose mode.

## 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_list(l)