The detail element is used to carry application-specific error information.
It may be annotated with any number of attributes from any namespace,
and may have any number of namespace-qualified element children.
The detail element must be present if the fault is the result of the recipient
being unable to process the Body element.
This element is not used to provide error information
in the case of the recipient being unable to process an element child of the Header element.
In such cases, error information is placed inside the Header element.