In the brotli data format (rfc7932) we left the concept of a container away altogether. In gzip there is a container format that allows specifying things that

In the brotli data format (rfc7932) we left the concept of a container away altogether. In gzip there is a container format that allows specifying things that are mostly meaningless (like having a reserved value for 'Amiga'). In JPEG XL there are two stream forms, one with and one without the container. Both work for normal use.