Here, a Mapping describes how a Texture should be applied to a Geometry, i.e. the UV coordinates of that geometry.
Our Mapping model corresponds to the X3D/X3DOM Texture Mapping but without the center attribute. Also there is no metadata attribute.
A Mapping can be applied to both Materials and Geometry instantiation. If it's applied to both, the Geometry mapping has higher priority than the Material mapping. Hereby the mappings are merged on attribute level, i.e. the Material mapping may define the scaling while the Geometry mapping adds some offset or rotation.