While David Megginson on XML-DEV is raising the issue of the multiple ways for indicating multiple output documents in XSLT, another long thread running on the XSL-LIST is discussing a similar problem with the "node-set" extension.

This extension (implemented with a different syntaxes by both XT and Saxon) works around a well known limitation of the XSLT 1.0 W3C Recommendation which doesn't allow result tree fragments to be handled as node sets. By allowing the conversion of result tree fragments into node sets, one can then apply templates to them.

As with the multiple documents extension, the discussion demonstrates a need for a way to define in a consistent way the most useful extensions, and a mechanism to bring these extensions back into the next releases of the recommendation.