Comparison operators

The comparison operators are ==,>,<,>=,<=,<> (alternate syntax !=). They can be used to compare literals of any data type and return a Boolean, depending whether the comparison is satisfied or not. Only values of the same type can be compared. Marked nulls can be compared only with marked nulls, since they are the only ones having unknown data type. Marked nulls are equal when they have the same identifier (i.e., the same marked null).