Unit test: uri.001
DocBook does not mandate any values for the type attribute, but several useful values have been suggested:
http://example.com/uri/without/a/type
http://example.com/uri/without/a/type/of/sometype
http://docbook.org/ns/docbook
http://xml.org/sax/features/namespaces
http://xml.org/sax/properties/declaration-handler
https://nwalsh.com/
https://norman.walsh.name/
https://docbook.org/schemas/
https://docbook.org