Companies Act, 1956
Sec 91 - Calls on shares of some class to be made on uniform basis
Where after the commencement of this Act, any calls for further share capital are made on shares, such calls shall be made on a uniform basis on all shares falling under the same class.
Explanation. : For the purposes of this section, shares of the same nominal value on which different amounts have been paid-up shall be deemed to fall under the same class.