XMDF3 mixed topology is not supported (paraview exit when reading the official example)
example of mixed topology, from url" https://www.xdmf.org/index.php/XDMF_Model_and_Format#Geometry
does not work in paraview 5.9/5.10. I suspect if mixed topology is actually supported, i did not find source code to deal with this
<Domain>
<Grid Name="Octahedron" GridType="Uniform">
<Topology TopologyType="Mixed">
<DataItem Dimensions="26" NumberType="Int" Precision="4" Format="XML">
16
8
3 0 1 4
3 0 1 5
3 1 2 4
3 1 2 5
3 2 3 4
3 2 3 5
3 3 0 4
3 3 0 5
</DataItem>
</Topology>
<Geometry GeometryType="XYZ">
<DataItem Rank="2" Dimensions="6 3" NumberType="Float" Precision="8" Format="XML">
-1. -1. 0.
-1. 1. 0.
1. 1. 0.
1. -1. 0.
0. 0. 1.
0. 0. -1.
</DataItem>
</Geometry>
</Grid>
</Domain>