x_list − Extract Cross-Over Information from the Data Base.
x_list [ leg1 ] [ leg2 ] [ −dataflags ] [ −Rwest/east/south/north ] [ −Xxbase ] [ −H ] [ −I ] [ −V ] [ −Ccorrfile ] [ −Zignorefile ]
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"]. | 
Wessel, P. XOVER: A Cross-over Error Detector for Track Data, Computers & Geosciences, 15, 333-346.