<catalog xmlns="urn:example:catalog">
  <book isbn="978-0-262-01063-2">
    <title>Functorial Data Migration</title>
    <author>David I. Spivak</author>
    <year>2012</year>
    <publisher>MIT Press</publisher>
  </book>
  <book isbn="978-3-540-40697-0">
    <title>Generalized Algebraic Theories and Contextual Categories</title>
    <author>John Cartmell</author>
    <year>1986</year>
    <publisher>Springer</publisher>
  </book>
</catalog>
