Retrieves a value from an XML document by evaluating an XPath expression.
Returns the string-value of the first-matching node. If the XPath expression does not evaluate to a node, the result is empty.
The return value is comparable to a string-value returned by <xsl:value-of> in XSLT. This contrasts with a 'deep copy' of the node, returned by USXSL.Node, and comparable to what <xsl:copy> returns in XSLT.
The required xml-document must be one of the following:
•A literal string that is an XML document.
•An alias previously connected to an in-memory XML document by calling the USXSL.SetXml method.
•A filename, or folderpath and filename.
If xml-document starts with "<" it is assumed to be a literal string that is an XML document. Otherwise, if it corresponds with a known alias produced by USXSL.SetXml, it is assumed to be that alias. Otherwise, it is assumed to be a reference to a file containing an XML document.
The required xpath-expression must be a valid XPath 1.0 expression.
The optional namespace-list is a list of namespace mappings for prefixes used in the XPath expression, separated by spaces.