Any of the following child elements may be specified (, in order)the specified order (i.e. filters must appear first, then optionally a trust engine, and finally one of the request construction elements.
|0 or more||A metadata filter applied to candidate metadata as it flows through the metadata pipeline|
|0 or 1||A custom |
|0 or 1||Constructs the metadata request URL based on the requirements of the Metadata Query Protocol|
|0 or 1||Constructs the metadata request URL by means of a simple transform based on substitution|
|0 or 1||Constructs the metadata request URL by means of a complex transform based on a regular expression|