Help understand leave policy with an example - accumulated to a maximum of 90 days?

EL can be availed in maximum of three parts in a year on prorated basis and each part should not be less than 3 days.
Sanctioning of leaves shall be at the discretion of Reporting Manager and HR / CEO.
 Un-availed leave can be accumulated to a maximum of 90 days.

This sort of condition prescribing a minimum no. of days of leave to be availed is rather unheard of. Rest of the condition is common.