Round tripping
Prefix filtering and renaming (allows using DTD for namespaced documents)
Switching between grammar versions using DOCTYPE and XPath
Example 6. Automatic selection between XSLT 1.0 and 2.0 schemas
<rules xmlns="http://purl.oclc.org/dsdl/nvdl/ns/structure/1.0" xmlns:jnvdl="http://jnvdl.sf.net"> <namespace ns="http://www.w3.org/1999/XSL/Transform" jnvdl:useWhen="@version = '1.0'"> <validate schema="1.0/xslt10.rng"/> </namespace> <namespace ns="http://www.w3.org/1999/XSL/Transform" jnvdl:useWhen="@version = '2.0'"> <validate schema="2.0/schema-for-xslt20.xsd"/> </namespace> </rules>