MeshLab is an excellent tool for manipulating mesh datasets and it is utilized in various application areas (e.g. Cultural heritage pipelines) today. It comes with a great X3D exporter which can handle texture, vertex/face-normal and vertex color. However, the tool creates always a ColorRGBA-node even so there is no alpha-data in the vertex color. Since ColorRGBA is in our proposed profile we added this node to better support MeshLab right now.
The example uses the ColorRGBA values to store the ambient occlusion values per vertex calculated in MeshLab