Semantics : ComparatorDecl

ComparatorDecl  ::=  ( < ( ( Number | String | Date ) ( - | + )? | Expr )? > )?

Used by:  

If an Expr is enclosed, it must be a user-defined comparator function. Or, it can use the predefined comparators for number, string and date/time. If no comparator is explicitly specified, it uses a natural comparator, which compares the Java object values or string values if that object is not comparable.