> parameters
such as <EM>:pos</EM>, <EM>:rot</EM>, <EM>:Euler</EM>, <EM>:rpy</EM>, etc. can be
used to specify the location and the orientation of the viewing coordinates.
However, viewing's <EM>:init</EM> provides easier way to determine the
rotation.
If only <EM>:target</EM> is given, view-line (-z axis) is determined to
pass the viewpoint and <EM>:target</EM> point, and the <EM>:view-right</EM>
vector is determined so that the x-axis is parallel to the xy-plane of the
world coordinates.
You may specify <