You are using PO integration between ERP and SNC, you have defined several MoT for one Transport lane and you want to specify in the xml, which one should be used.
You can maintain this number in the TransportMeansDescriptionCode XML tag.
You can check the code which should be used for a specific MoT in the following customizing:
Maintain Means of Transport
In the first column you see the name of the MoT, in the third you see the code. In the xml tag TransportMeansDescriptionCode you have to specify the code with a leading zero. I looks like this for 0001 Truck -> 0031.
This way the xml will be processed and on the WebUI you will be able to see the specified MoT.