law: Transfer of Property Act, 1882
  28. Ulterior transfer conditional on happening or not
  
  happening of specified event
  On a transfer of property an interest therein may be created to
  
  accrue to any person with the condition superadded that in case a specified
  
  uncertain event shall happen such interest shall pass to another person, or
  
  that in case a specified uncertain event shall not happen such interest shall
  
  pass to another person. In each case the dispositions are subject to the rules
  
  contained in sections 10, 12, 21, 22, 23, 24, 25 and 27.