In what way is the so called modified duration measure a modification of the Macaulay measure?

In what way is the so called modified duration measure a modification of the Macaulay measure? 

Ans. For calculating Modified duration, we first need to calculate Macaulay measure. The formula of modified duration divides the Macaulay measure by 1 plus bond’s average yield to maturity which is obtained by dividing YTM by n. Modified duration is calculated as:

n = number of coupon periods per year measure YTM = the bond’s yield to maturity Hence, it is modification of Macaulay’s measure.