law: Transfer of Property Act, 1882
  79. Mortgage to secure uncertain amount when maximum is
  
  expressed
  If a mortgage made to secure future advances, the performance of
  
  an engagement or the balance of a running account, expresses the maximum to be
  
  secured thereby, a subsequent mortgage of the same property shall, if made with
  
  notice of the prior mortgage, be postponed to the prior mortgage in respect of
  
  all advances or debits not exceeding the maximum, though made or allowed with
  
  notice of the subsequent mortgage.
  Illustration
  A mortgages Sultanpur to his bankers, B & Co., to secure the
  
  balance of his account with them to the extent of Rs. 10,000. A then mortgages
  
  Sultanpur to C, to secure Rs. 10,000, C having notice of the mortgage to B
  
  & Co., and C gives notice to B & Co. of the second mortgage. At the date
  
  of the second mortgage, the balance due to B & Co. does not exceed Rs.
  
  5,000. B & Co. subsequently advance to A sums making the balance of the
  
  account against him exceed the sum of Rs. 10,000. B & Co. are entitled, to
  
  the extent of Rs. 10,000, to priority over C.