<Ol> <Li> The time at which a person attains a particular age expressed in years shall be the commencement of the anniversary corresponding to the date of (their) birth . </Li> <Li> Where a person has been born on February 29 in a leap year, the relevant anniversary in any year other than a leap year shall be taken to be March 1 . </Li> <Li> This section shall apply only where the relevant anniversary falls on a date after the date of commencement of this Ordinance . </Li> </Ol> <Li> The time at which a person attains a particular age expressed in years shall be the commencement of the anniversary corresponding to the date of (their) birth . </Li> <Li> Where a person has been born on February 29 in a leap year, the relevant anniversary in any year other than a leap year shall be taken to be March 1 . </Li> <Li> This section shall apply only where the relevant anniversary falls on a date after the date of commencement of this Ordinance . </Li>

Where did the idea of leap year come from