# X_LIST

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
REFERENCES

## NAME

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

## SYNOPSIS

x_list [ leg1 ] [ leg2 ] [ −dataflags ] [ −R west/east/south/north ] [ −X xbase ] [ −H ] [ −I ] [ −V ] [ −C corrfile ] [ −Z ignorefile ]

## 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.