Educational istitution-exemption section

i guess section 11 ...85% of income need to be reinvested in the same activity & 15% hve to be investment in specfieed securities

EXEMPTE U/S 10(23) (iiiad) any university or other educational institution existing solely for educational purposes and not for purposes of profit if the aggregate annual receipts of such university or educational institution do not exceed the amount of annual receipts as may be prescribed26; or And [(vi) any university or other educational institution existin solely for educational purposes and not for purposes of profit, other than those mentioned in sub-clause (iiiab) or sub-clause (iiiad) and which may be approved by the prescribed authority;

Can u pls specify what are the speceified limits for the income to be exempt ?