e
If eTag is provided in the response body, it may also be provided as a header per the normal etag convention. Entity tags are used for comparing two or more entities from the same requested resource. HTTP/1.1 uses entity tags in the etag (section 14.19), If-Match (section 14.24), If-None-Match (section 14.26), and If-Range (section 14.27) header fields.