Returns the name of the XSLT 1.0 data type that a given variable is currently cast to.
The return value is one of the string values nodeset, string, number, boolean.
The required xpath must evaluate to a string that is the name of an instantiated variable. If there is no instantiated variable by that name, the return value is nodeset.
The result of the following is boolean:
A variable may be initialised and have the empty string ( '' ) as a value. The result of the following is string:
If no variable by the name of "defined" is instantiated, the result of the following is nodeset: