I'm now re-reading the Xdata_manual.pdf - pages for Web Applications with TMS WebCore and beginning to get a feel from how I think you parse the URL/$model, to fulfill your TXDataWebDataSet EntitySet Name, i.e. EntityTypes for list and then EntityContainers for the actual data.
Another Gotcha is the CORS, so when I run my little application, I get "not connected" and in the console (you see - learning slowly) I get: SEC7120: [CORS] The origin 'http://localhost:8000' did not find 'http://localhost:8000' in the Access-Control-Allow-Origin response header for cross-origin resource at 'http://localhost:2001/tms/FB15DataDTest/$model'.