When you tag a ViewModelColumn with BlobDownloadLink - the UI will render this as a download. It will use the controller named GetVMFile to allow for a download of content type application/octet-stream. If your request has accept-encoding:gzip - then we will gzip the file on the server before sending it back. The server will tag the response header like this: content-encoding:gzip content-length:16660 content-type:application/octet-stream

The content-length will in this case be the zipped length