The player also suffers a penalty to XP if they are too far above or below the monster's level. There is a safe level range where no penalty is applied, which is equal to three, plus one for every sixteen complete player levels. Any additional level difference in excess of this safe range is called the Effective Difference.
So a level 24 character has a safe band of 3+1=4 levels. So from Monster level 20 to 28, there is an effective level difference of 0. At Monster Levels 19 and 29, the Effective level difference is 1. The Effective Difference matters in either direction.
The formula then applied is: Final Experience = [(PlayerLevel + 5) / (PlayerLevel + 5 + EffectiveDifference2.5)]1.5. In our example, a level 24 character receives 95% experience for level 19 monsters, 52.5% experience for level 17 monsters, and 20% experience for level 15 monsters.