[xsl] Serializing elements in CDATA, based on an attribute value

["cmarchand@xxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hello,
In a document, I write many tags of metadata. Part of them, based on 
@code value (debug & info), MUST be serialized with a CDATA content.

With this input :
<metadata code="dummy">Standard serialization</metadata>
<metadata code="debug">C-Data serialization</metadata>
<metadata code="foe">Standard serialization</metadata>
<metadata code="info">C-Data serialization</metadata>

I do expect this :
<metadata code="dummy">Standard serialization</metadata>
<metadata code="debug"><![CDATA[C-Data serialization]]></metadata>
<metadata code="foe">Standard serialization</metadata>
<metadata code="info"><![CDATA[C-Data serialization]]></metadata>

What must I define as serialization parameters to get this ? I use Saxon 
9.7EE, so I can use Saxon extensions.

Thanks in advance,
Christophe