law: Registration Act, 1908
  50. Certain registered documents relating to land to take
  
  effect against unregistered documents
  (1) Every document of the kinds mentioned in clauses (a), (b),
  
  (c) and (d) of section 17, sub-section (1), and clauses (a) and (b) of section
  
  18, shall, if duly registered, take effect as regards the property comprised
  
  therein, against every unregistered document relating to the same property, and
  
  not being a decree or order, whether such unregistered document be of the same
  
  nature as the registered document or not.
  (2) Nothing in sub-section (1) applies to leases exempted under
  
  the proviso to sub-section (1) of section 17 or to any document mentioned in
  
  sub-section (2) of the same section, or to any registered document which had
  
  not priority under the law in force at the commencement of this Act.
  Explanation: In cases where Act No. XVI of 1864 or the
  
  Indian Registration Act, 1866, was in force in the place and at the time in and
  
  at which such unregistered document was executed, "unregistered"
  
  means not registered according to such Act, and, where the document is executed
  
  after the first day of July, 1871, not registered under the Indian Registration
  
  Act, 1871, or the Indian Registration Act, 1877, or this Act.