$xpc->registerNS($prefix, $ns) defines a prefix. (Not the only one, though.) You can't use a prefix you haven't defined. But it's possible to build XPaths that don't use prefixes using namespace-uri() and local-name().

In reply to Re^3: Using XPaths with XML::LibXML and XPathContext by ikegami
in thread Using XPaths with XML::LibXML and XPathContext by worik

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