I get it now. (I was getting confused between the namespace DAV: and the namespace DAV, duh!) Is it compulsory to register a namespace prefix? I can seem to find no way of using a fully qualified XPath. For a namespace NS calling registerNs(NS, NS) works. Is that the only way?

If you want to use a prefix in xpath, a prefix that doesn't occur in the xml, you have to register it

You don't have to use a prefix in xpath, just write longer xpath 

//*[ local-name() != 'propfind'
     and contains(local-name(), 'prop')
     and namespace-uri() = 'DAV:' ]

[download]

It all works the same 

$ cat  dav-rfc4918-dingaling.xml
<?xml version="1.0" encoding="utf-8"?>
<D:propfind xmlns:D="DAV:">
  <D:prop xmlns:R="http://ns.example.com/boxschema/">
    <R:bigbox/>
    <R:author/>
    <R:DingALing/>
    <R:Random/>
  </D:prop>
</D:propfind>

$
$ cat  dav-rfc4918-allprop.xml
<?xml version="1.0" encoding="utf-8" ?>
<D:propfind xmlns:D="DAV:">
  <D:allprop/>
</D:propfind>
$
$ cat  dav-rfc4918-propname.xml
<?xml version="1.0" encoding="utf-8" ?>
<propfind xmlns="DAV:">
  <propname/>
</propfind>
$
$
$ xmllint.exe --xpath " //*[ local-name() != 'propfind' and contains(l
+ocal-name(), 'prop
') and namespace-uri() = 'DAV:' ]  "     dav-rfc4918-dingaling.xml
<D:prop xmlns:R="http://ns.example.com/boxschema/">
    <R:bigbox/>
    <R:author/>
    <R:DingALing/>
    <R:Random/>
  </D:prop>
$
$ xmllint.exe --xpath " //*[ local-name() != 'propfind' and contains(l
+ocal-name(), 'prop
') and namespace-uri() = 'DAV:' ]  "     dav-rfc4918-allprop.xml
<D:allprop/>
$
$ xmllint.exe --xpath " //*[ local-name() != 'propfind' and contains(l
+ocal-name(), 'prop
') and namespace-uri() = 'DAV:' ]  "     dav-rfc4918-propname.xml
<propname/>
$

[download]

I've said as much in Re: xmlns and XML::LibXML ( local-name() ), Re^3: xmlns and XML::LibXML

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

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