The standard way to define a three dimensional vector is by its coordinates.
This gives a single vector with coordinates (1,1,0) with respect to the x, y , z coordinate system. A second way to define a specimen directions is by its spherical coordinates, i.e. by its polar angle and its azimuth angle. This is done by the option polar.
Finally, one can also define a vector as a linear combination of the predefined vectors xvector, yvector, and zvector