CDXWEB is a format that replaced its predecessor - CDXFB.

Since we have a lot of customers that still use CDXFB models they created earlier, we decided that Web Toolkit should continue to support them. This implies usage of the universal reader - ModelData_ModelReader - capable of distinguishing and reading both formats.

From CAD Exchanger SDK's side, CDXWEB completely superseded CDXFB in 3.20.0. The latter has been renamed to CDXWEB, and for source compatibility it's also defined as an alias for CDXWEB. So even if you specify CDXFB as an export format in SDK, the result will actually be a CDXWEB model (although with CDXFB extension). You can still use "model.cdxfb" as file name, but we recommend to change ".cdxfb" to ".cdxweb" to avoid confusion of your developers.