OBIS sitemap missing important header

[jmckenna]

• snippet of OBIS sitemap:

  <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
  <loc>https://obis.org/dataset/efa02fe9-6b5b-4173-85e7-912f71921fe7</loc>
  <changefreq>weekly</changefreq>
  <priority>1</priority>
  </url>
  ...
  </urlset>

• missing the important header (first line):

  <?xml version="1.0" encoding="UTF-8"?>

• one result of that is you can see the browser also doesn't know the type of that file
  • click on the sitemap link & the [Firefox] browser does not display the xml, it just downloads it