How to sort sibling elements based on attribute of chi

Wendell,

Thanks for the solution. The key concept that I learned was how to
select and output the preceding and following siblings of
<Annotation>.

I omitted a key bit of information in my example: <Root> should have
been named <Parent>, since the parent element of Annotation is not the
document root element:

<Root>
   <Junk>junk</Junk>
   <Parent>
       <Stuff>stuff</Stuff>
       <Annotation>
           <Comment Priority="1">my first comment</Comment>
       </Annotation>
       <Annotation>
           <Comment Priority="3">my third comment</Comment>
       </Annotation>
       <Annotation>
           <Comment Priority="2">my second comment</Comment>
       </Annotation>
       <Bother>bother</Bother>
   </Parent>
</Root>

As a consequence, I didn't to use this template to produce output when
there is no Annotation:

<xsl:template match="/*[not(Annotation)]" priority="2">
 <xsl:apply-templates/>
</xsl:template>

Instead, I put a test for <Annotation> into the template - which might
not be the most elegant solution, but it works:

   <xsl:template select="Parent">
       <xsl:choose>
           <xsl:when test="Annotation">
               <xsl:apply-templates
select="Annotation[1]/preceding-sibling::*"/>
               <xsl:apply-templates select="Annotation">
                   <xsl:sort select="*/@Priority"/>
               </xsl:apply-templates>
               <xsl:apply-templates
select="Annotation[last()]/following-sibling::*"/>
           </xsl:when>
           <xsl:otherwise>
               <xsl:apply-templates select="*"/>
           </xsl:otherwise>
       </xsl:choose>
   </xsl:template>

Thanks again for your help!

--
Philip