The two current answers are wrong:
/*/*
does not select all nodes that are children of the top node. It does not select any text nodes, processing-instructions or comments that are children of the top element.
One XPath expression that select all nodes that arte children of the top element is:
/*/node()
//
is not a syntactically correct XPath expression; according to the XPath Spec:
// is short for
/descendant-or-self::node()/
Do note the beginning of an unfinished location step at the very end of the expanded abbreviation. If nothing is added to it, the whole XPath expression containing the abbreviation is finished and, therefore, syntactically incorrect.
Another note is that the //
abbreviation is not necessary in specifying the selection of all nodes that are children of the top element. If you wanted to select all nodes in the XML document that descend from the top element, then one XPath expression that select these is:
/*//node()