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The VRML 1.0 Final Specification explains this:
VRML uses a Cartesian, right-handed, 3-dimensional coordinate system. By default, objects are projected onto a 2-dimensional device by projecting them in the direction of the positive Z axis, with the positive X axis to the right and the positive Y axis up. A camera or modelling transformation may be used to alter this default projection. The standard unit for lengths and distances specified is meters. The standard unit for angles is radians.
Vectors are used to specify directions and points, relative to the origin. VRML defines two types of vector:
Any of the displacements - x, y or z - can be negative. There are also types for lists of vectors - MFVec2f and MFVec3f.
To apply a rotation to an object, you need to specify the axis of rotation using a vector, and the angle of rotation.
You can set the starting point of the viewer, by defining a perspective camera. With this kind of view objects that are further away appear smaller. It has these properties: