XML schema is some other XML file which like DTD defines the type of document contents. Ths most famous is W3C XML schema but there could other means to declare the document. An example below shows generic XML schema content. Its root element is schema. Besides namespace-prefix mapping it can contains some set of attributes. Here we enable full-qualified names for elements and names only (without namespace prfixes) for attributes:

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

////////////// schema declaration, customization:


////////////// declaration of our root element:

  <xs:element name="purchase-order">