On Sat, 23 Feb 2019 at 13:40, Tom Morris <[log in to unmask]> wrote:

> Not sure whether or not it's also available through content negotiation.

Yep, but with an odd use of media types; asking for application/xml
gives you HTML :O

$ curl -I -H "Accept: application/rdf+xml"
https://portal.issn.org/resource/ISSN-L/1084-5305
HTTP/1.1 200 OK
Date: Sat, 23 Feb 2019 18:45:00 GMT
Server: Apache/2.4.25 (Debian)
X-Drupal-Cache: MISS
Expires: Sun, 19 Nov 1978 05:00:00 GMT
Cache-Control: no-cache, must-revalidate
X-Content-Type-Options: nosniff
Content-Type: application/xml; charset=utf-8