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XSD datatype

xs:anyURI

A URI reference — validated so loosely that almost any string passes, which makes it weaker than it looks.

xs:anyURI accepts absolute URIs, relative references, and fragments. In practice the specification's requirements are so permissive that most processors accept nearly any string that has no spaces, and some accept those too.

It is a documentation aid rather than a constraint. If a value must be an absolute https URL, a pattern facet is the only thing that will enforce it.

Lexical space
A URI reference, per RFC 2396 as amended — in practice, almost anything.
Derives from
Primitive type
Category
Other types
Facets
length, minLength, maxLength, pattern, enumeration, whiteSpace

What validates

Every literal below is put through the schema validator on each test run, against the schema at the foot of this page.

  • https://example.com/
  • /relative/path
  • #fragment
  • urn:isbn:0451450523
  • not a url

What does not

Nothing — this type accepts any legal XML character content. That is worth knowing: it constrains nothing on its own, so any real restriction has to come from a facet.

What catches people out

  • It validates almost anything, including 'not a url'. Do not rely on it to mean 'this is a link'.
  • Nothing is fetched or resolved. A namespace URI is an identifier, not an address.
  • Use a pattern facet when the scheme actually matters.

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