xpath optional attribute with inner attributes

I have this xml with a nested element which is optional and I have to make a csv file with attributes from the hierarchy even when the optional attribute is not present.

here is the xml data file:

    <dataroot xmlns:xsi="http://ift.tt/ra1lAU" xmlns="http://ift.tt/1xcff8U">
    <ELEMENTS>
        <COUNTRY cod_cnt="030">
            <AS cod_as="030308">
             <CONTRACT num_CONTRACT="8715167"/>
             <CONTRACT num_CONTRACT="8715224"/>
            </AS>
         <AS cod_as="030309"/>
    </COUNTRY>
    </ELEMENTS>
</dataroot>

suppose i need the elements that have a CONTRACT tag and the AS tag even if it hasn't a CONTRACT child. I've wrote something like that but I'm stuck:

<xsl:for-each select="/doc:dataroot/doc:ELEMENTS/doc:COUNTRY/doc:AS/doc:CONTRACT">
    <xsl:value-of select="../../@cod_cnt"/>@<xsl:value-of select="../@cod_as"/>
    @<xsl:value-of select="@num_CONTRACT"/>@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@0@D<xsl:text> </xsl:text>
</xsl:for-each>

I know I miss a sort of union but can't go further.