The IResultDocumentHandler to be used at run-time to process the output
produced by any xsl:result-document instruction with an href
attribute.
In the absence of a user-supplied result document handler, the href
attribute of the xsl:result-document instruction must be a valid relative
URI, which is resolved against the value of the BaseOutputUri property,
and the resulting absolute URI must identify a writable resource (typically
a file in filestore, using the file: URI scheme).