Are email addresses without "mailto:" allowed as IRIs?

Question

In the RDF Turtle documentation from W3C I came across two examples (16 and 17) where an email address was used as an IRI:

_:b <http://xmlns.com/foaf/0.1/mbox> <[email protected]> .

As I understand it, email addresses are allowed as URIs when preceded with the appropriate scheme, i.e. mailto:[email protected]. If the email address in the above example should be a valid URI then the statement should actually read:

_:b <http://xmlns.com/foaf/0.1/mbox> <mailto:[email protected]> .

Is this an error in the documentation or do IRIs (as opposed to URIs) not require a scheme?

Answer 1

While I think it makes more sense to use something like mailto:[email protected] in these examples, it appears that they're still syntactically legal. They're just resolved as relative URIs against the base. E.g., when I use Jena's rdfcat to convert from Turtle I get the following output in Turtle and RDF/XML.

@prefix : <urn:ex:> .
@base <http://example.org> .

:a :hasEmail <[email protected]>.

Output in Turtle and RDF/XML:

@prefix :      <urn:ex:> .

:a      :hasEmail  <http://example.org/[email protected]> .

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns="urn:ex:">
  <rdf:Description rdf:about="urn:ex:a">
    <hasEmail rdf:resource="http://example.org/[email protected]"/>
  </rdf:Description>
</rdf:RDF>