Test Vector Problem

I am having trouble understanding one the tests from 
01-phaos-xmldsig-two.zip. I was hoping somebody could point out 
my misunderstanding.

The signature-big.xml file contains the following dsig:Reference,

<dsig:Reference Id="reference-xpath-transform" 
URI="document.xml">
    <dsig:Transforms>
        <dsig:Transform 
Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
            <XPath>@*</XPath>
        </dsig:Transform>
        <dsig:Transform 
Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"/>
    </dsig:Transforms>
    <dsig:DigestMethod 
Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
    
<dsig:DigestValue>gC+C369XMEjx8b6SsFYAKQP4Gzo=</dsig:DigestValue>
</dsig:Reference>

I was getting a failure on this so I checked the digest value and 
it matches against the following subset of document.xml.

<player bats="left" id="10012" throws="right"></player>

My question is that given the XPath transform only matches 
elements with attributes how come the attributes are being 
included in the C14N.

Thanks for any help you can offer.
Kevin