trying to do a transform and everything is working but I am losing the xsi:schemalocation entry in the output XML

Missing:
xsi:schemaLocation="http://www.ourbedandbreakfast.com/reserve_schema.xsd"

Original Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<bb3:Reservations xmlns:bb3="http://www.ourbedandbreakfast.com/sample1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ourbedandbreakfast.com/reserve_schema.xsd">
    <bb3:Reservation RoomNum="106" InvoiceNum="BB3002">
        <bb3:Customer FirstName="Tom" LastName="Cruise" />
        <bb3:Customer FirstName="Nicole" LastName="Kidman" />
    </bb3:Reservation>
    <bb3:Reservation RoomNum="206" InvoiceNum="BB5010">
        <bb3:Customer FirstName="Tom" LastName="Cruise" />
    </bb3:Reservation>
    <bb3:Reservation RoomNum="506" InvoiceNum="BB6020">
        <bb3:Customer LastName="Madonna" />
    </bb3:Reservation>
</bb3:Reservations>

XSLT:
<?xml version="1.0"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:bb3="http://www.ourbedandbreakfast.com/sample1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ourbedandbreakfast.com/reserve_schema.xsd">
<xsl:output method="xml" indent="yes" encoding="UTF-8"/>
<xsl:template match="bb3:Reservations">
  <bb3:CustomerVisits>
  <xsl:for-each-group select="bb3:Reservation/bb3:Customer" group-by="concat(@FirstName, '~', @LastName)">
         <bb3:Booking>
             <xsl:copy>
               <xsl:copy-of select="@*"/>
               <xsl:apply-templates mode="copy"/>
             </xsl:copy>
    <xsl:for-each select="current-group()">
      <InvoiceNum><xsl:value-of select="../@InvoiceNum"/></InvoiceNum>
    </xsl:for-each>
    </bb3:Booking>
  </xsl:for-each-group>
   </bb3:CustomerVisits>
</xsl:template>
</xsl:stylesheet>

Final Output:

<?xml version="1.0" encoding="UTF-8"?>
<bb3:CustomerVisits xmlns:bb3="http://www.ourbedandbreakfast.com/sample1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
 <bb3:Booking>
  <bb3:Customer FirstName="Tom" LastName="Cruise"/>
      <InvoiceNum>BB3002</InvoiceNum>
      <InvoiceNum>BB5010</InvoiceNum>
 </bb3:Booking>
 <bb3:Booking>
  <bb3:Customer FirstName="Nicole" LastName="Kidman"/>
      <InvoiceNum>BB3002</InvoiceNum>
 </bb3:Booking>
 <bb3:Booking>
  <bb3:Customer LastName="Madonna"/>
      <InvoiceNum>BB6020</InvoiceNum>
 </bb3:Booking>
</bb3:CustomerVisits>

Putting an attribute on the xsl:stylesheet element won't cause it to be added to the result document.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

This change seems to help, but the final output changes the order of the namespaces (xsi comes before bb3).

Why would that be happening, that is the ordering changing?

<xsl:template match="bb3:Reservations">
  <bb3:CustomerVisits xmlns:bb3="http://www.ourbedandbreakfast.com/sample1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ourbedandbreakfast.com/reserve_schema.xsd">
  <bb3:CustomerVisits>
  <xsl:for-each-group select="bb3:Reservation/bb3:Customer" group-by="concat(@FirstName, '~', @LastName)">
         <bb3:Booking>
             <xsl:copy>
               <xsl:copy-of select="@*"/>
               <xsl:apply-templates mode="copy"/>
             </xsl:copy>
    <xsl:for-each select="current-group()">
      <InvoiceNum><xsl:value-of select="../@InvoiceNum"/></InvoiceNum>
    </xsl:for-each>
    </bb3:Booking>
  </xsl:for-each-group>
   </bb3:CustomerVisits>
</xsl:template>

As with attributes, the order of namespace declarations within an element start tag has no significance and you can't control it.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Okay thats good to know.

Makes sense because oXygen using the Saxon8B engine with the same XSL does get the ordering right.

But my JAXP code using the saxon8b.jar does not. So my JUnit test fails when the output is compared to the expected file.

Its odd that using the same engine is producing different results though. Any thoughts?

No, it's not at all odd. Because order is important, the processor can use data structures such as hash tables that don't preserve order.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

>Because order is important
s/important/unimportant/

When comparing test results against reference results, consider (a) canonicalizing both first (see "Canonical XML"), or (b) using the XPath 2.0 deep-equals() function.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Could you suggest a template that I could use to maybe copy all namespaces and schema locations from the original "<bb3:Reservations" and then place after "<bb3:CustomerVisits "

It seems that there is probably a better way then hard coding them.

Thanks for the tip on the test case comparisons, I will look into those suggestions.