setCanonicalMethod generates incomplete string....

[agente_mor]

With the following code:
$objDSig->setCanonicalMethod(XMLSecurityDSig::EXC_C14N);

It is generated the following:
<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>

How can I change the first instruction shown in order to generate the following?
http://www.w3.org/TR/2001/REC-xml-c14n-20010315

which is reported by a validator of xml messages.

thanks
mario

[agente_mor]

Found it,
instead of EXC_C14N
just write C14N
mario