XSLT 2.0: validate output against a Schematron Schema?

Hi Folks,

Consider a stylesheet which processes some input, and then outputs this
document:

<?xml version="1.0"?>
<Document classification="secret">
    <Para classification="unclassified">
          One if by land, two if by sea;
    </Para>
    <Para classification="confidential">
          And I on the opposite shore will be,
          Ready to ride and spread the alarm
    </Para>
    <Para classification="unclassified">
          Ready to ride and spread the alarm
          Through every Middlesex, village and farm,
    </Para>
    <Para classification="secret">
          For the country folk to be up and to arm.
    </Para>
</Document>

I know that XSLT 2.0 has the capability to validate the output, using
default-validation="strict" and other means.

I assume the default validation language is W3C XML Schema, correct?

Does the XSLT specification allow for validation using other schema
languages, such as Schematron and Relax NG?

For the above output document, I want to do two types of validation:

1. Grammar-based validation - validate that the contents of <Document>
is one or more <Para> elements, etc.

2. Co-constraint validation - validate that no Para has a
classification higher than the overall Document's classification.

Thus, I would like the output document to be validated by two schemas:

1. W3C XML Schema or Relax NG

2. Schematron

Does the XSLT specification allow for validation against multiple
schemas?

If yes, are there any processors that provide this capability?

RECAP

1. Is the W3C XML Schema language the default validation language for
XSLT 2.0?

2. Can an XSLT 2.0 stylesheet validate an input or output document
using other schema languages, in particular Schematron and Relax NG?

3. Can an XSLT 2.0 stylesheet validate an input or output document
against multiple different schema languages?

4. Are there any XSLT 2.0 processors that implement multi-language
validation?

/Roger