{xpath:string:query:attr:delimiter}

Runs an XPath query against an XML or HTML string and returns the matching content. The first parameter is the markup to search - usually a remote page or feed loaded with the include command, but any literal XML/HTML string works. The second parameter is the XPath query (for example //title, //book[2]/title, or //book[@id="b2"]/author). The engine first tries a strict XML parse and falls back to a more tolerant HTML parse if that fails. By default only the first matching node is returned, as its text value. The optional third parameter changes what is returned from each match: give an attribute name to return that attribute (for example id or width), or the literal XML to return the matched node as inner markup. The optional fourth parameter is a delimiter: supply it to return all matching nodes joined by that delimiter instead of just the first - note the delimiter is appended after every match, including the last, so a trailing delimiter remains. A query that matches nothing returns an empty string; markup that cannot be parsed at all returns an error message. Because a colon separates parameters, an XPath axis written with a double colon such as following-sibling must be escaped in the query as following-sibling#:#: so the colons are not read as parameter separators.