floor : NTP ;
-- This feature returns the highest integral value which is less
-- than self.
ceiling : NTP ;
-- This feature returns the lowest integral value which is greater
-- than self.
round : NTP ;
-- This feature returns the result of rounding self to the nearest
-- integral value.
truncate : NTP ;
-- This feature returns the result of discarding any fractional part
-- of the value of self.