| SAXONICA | 
The simplest comparison operators are eq, ne, lt
            le, gt, ge. These compare two atomic values of the same type,
            for example two integers, two dates, or two strings. In the case of strings, the default collation
            is used (see 
            saxon:collation). 
            If the operands are not atomic values, an error is raised.
         
The operators =, !=, <, <=,
            >, and >= can compare arbitrary sequences. The result is true
            if any pair of items from the two sequences has the specified relationship, for example
            $A = $B is true if there is an item in $A that is equal to
            some item in $B. If an argument is a node, Saxon currently uses its string
            value in the comparison, not its typed value as required by the XPath 2.0 specification.
         
The operators is and isnot test whether the operands represent the same
            (identical) node. For example, title[1] is *[@note][1] is true if the first title
            child is the first child element that has a @note attribute. If either operand is an
            empty sequence the result is an empty sequence (which will usually be treated as false).
         
The operators << and >> test whether one node precedes
            or follows another in document order.