The `VNL` module contains a portion of the `VXL` project from

  https://github.com/vxl/vxl.git

Documentation about the library can be found at

  https://vxl.github.io/

See [UpdatingThirdParty.md](https://github.com/InsightSoftwareConsortium/ITK/blob/master/Documentation/Maintenance/UpdatingThirdParty.md) for details and instructions to update from upstream.