Section 273. Rapid transit sinking fund of the city of New York

There is
  hereby continued the fund known as the "rapid transit  sinking  fund  of
  the  city of New York" which shall have for its purpose the amortization
  and redemption of all corporate stock of the city of New York issued  on
  and  after  the  first  day  of January, nineteen hundred ten, for rapid
  transit purposes, excepting that issued since  the  first  day  of  July
  nineteen hundred eighty-one which is redeemable from the general sinking
  fund  or  any other sinking fund established pursuant to chapter 11-A of
  this charter.