namespaces [--registered|:r] [expression]
For each node in a given node-list lists
all namespaces that are valid the scope of the node.
Namespaces are listed in the form of
preceded by a canonical xpath of the corresponding node
on a separate line.
flag is used, list also namespaces registered with the
in XSH syntax.
If called without the
--registered flag and
no xpath is given, lists namespaces
in the scope of the current node.