XSL Crossref between 2 documents / srcfile and ID

Hello everybody

I am newbie in framemaker 15.

I'm lost....  and I need your help.

I have a problem to make a link between 2 document with xsl

I have an Xref element, for the external cross-references, where

DTD

<!ELEMENT Xref EMPTY>

<!ATTLIST Xref

  Format CDATA #IMPLIED

  srcfile CDATA #IMPLIED

>

RW

element "Xref "

  {

  is fm cross-reference element;

  attribute "Format" is fm property cross-reference format;

  }

in my document B.xml where is the Xref :

<Xref Format = "X_Text" srcfile = "A.xml#CHDJCICFE0"/>

in my document A.xml, where is the target:

<Abv ID = "CHDJCICFE0">Toto</Abv>

How i do in XSL, to select the content of the element Abv ---> Toto

How make with one attribute which has an "ID", and the other attribute which has a "srcfile"?

<xsl:template match="Xref">

      <A HREF="{@srcfile}" style="text-decoration:none;text-align:left;color:blue">

          <xsl:choose>

               <xsl:when test="@Format='X_Text'">

                     <xsl:value-of select="????????????????"/>

               </xsl:when>

          </xsl:choose>

     </A>

</xsl:template>

In advance, thank you very much

Jean Claude