Open content is an XSD 1.1 feature that allows a schema document to declare that all types
defined in the schema are automatically extensible by the addition of child elements or
further attributes, typically in a different namespace from the
targetNamespace of the schema document.
The facility allows a complex type to specify open content with mode "interleave" or "suffix", allowing arbitrary elements (satisfying a wildcard) to be added either anywhere in the content sequence, or at the end.
At the level of a schema document, the
defaultOpenContent option defines
the default open content mode for all types defined in the schema document (or, for all
types except those with an empty content model).
defaultAttributes attribute of the
element defines a default attribute wildcard to be permitted for all complex types
defined in the schema document.