The root element of SVG (svg_type) and the root element of X3D (x3d_type) have a Concept Bridge.
When a svg_type element is encountered in the source file , a x3d_type must be created in the target file.
When a svg_type element is encountered, a scene_type must also be created in the target file.
In this case, there is an ambiguity in the system. MAFRA does not know the conditions which results in the
creation of either x3d_type or scene_type.
In this case Extensional Specification is used to clarify the conditions which need to be met before the mapping occurs.
For each Concept Bridge between two objects, there must be a unique Extensional Specification. It is acceptable for one of
the Extensional Specifications to be not present.
The Extensional Specification between svg_type and x3d_type is not present.
The Extensional Specification between svg_type and scene_type is the presence of the cirlce_type
child element of svg_type. This is specified textually below.
In the target X3D, we need to specify that x3d_type is a parent element of scene_type. We do this by
using a Copy Relation. This states that whenever there is a relationship between two objects in the source ontology, a relationship
must be created between two specified objects in the target ontology. In the example above, a relationship between svg_type
and circle_type results in a relationship being created between x3d_type and scene_type.