-Y is +X   ISOY is the value of arithmetic expression X
+X =:= +Y   ISOthe results of evaluating terms X and Y as arithmetic expressions are equal.
+X =\= +Y   ISOthe results of evaluating terms X and Y as arithmetic expressions are not equal.
+X < +Y   ISOthe result of evaluating X as an arithmetic expression is less than the result of evaluating Y as an arithmetic expression.
+X >= +Y   ISOthe result of evaluating X as an arithmetic expression is not less than the result of evaluating Y as an arithmetic expression.
+X > +Y   ISOthe result of evaluating X as an arithmetic expression X is greater than the result of evaluating Y as an arithmetic expression.
+X =< +Y   ISOthe result of evaluating X as an arithmetic expression is not greater than the result of evaluating Y as an arithmetic expression.