Flexcom uses a number of axis systems. Of these, the most important are the global or XYZ axes. These are the axes in which many (though by no means all) coordinates and loads are input, they are the axes in which the total system equations of motion are assembled and solved internally by Flexcom, and they are finally the axes in which motions and reactions at restrained locations are output. In this system, the global X axis is vertical, with the global Y and Z axes lying in a horizontal plane such that the system is right-handed. Zero datum is located at X=0, so for example, if you are using the default flat seabed profile, then the global Y and Z-axes both lie on the seabed. See below:
Global Axes