law: Companies Act, 1956
  Sec 106     -    
  
  Alteration of rights of holders of special classes of shares 
  Where the share capital of a company is divided into different
  
  classes of shares, the rights attached to the shares of any class may be varied
  
  with the consent in writing of the holders of not less than three-fourths of
  
  the issued shares of that class or with the sanction of a special resolution
  
  passed at a separate meeting of the holders of the issued shares of that
  
  class  :
  (a) if provision with respect to such
  
  variation is contained in the memorandum or articles of the company, or
  (b) in the absence of any such provision in
  
  the memorandum or articles, if such variation is not prohibited by the terms of
  
  issue of the shares of that class.