2010 New York Code
RPP - Real Property
Article 9 - (290 - 336) RECORDING INSTRUMENTS AFFECTING REAL PROPERTY
316 - Indexes.

§ 316. Indexes. Each recording officer must provide, at the expense of
  his  county,  proper  books  for  making  general indexes of instruments
  recorded in his office, and must form indexes therein, so as  to  afford
  correct  and  easy reference to the records in his office. There must be
  one set of  indexes  for  mortgages  or  securities  in  the  nature  of
  mortgages  and  assignments of rent; and another set for conveyances and
  other instruments not intended as  such  mortgages  or  securities,  and
  executory  contracts for sale, purchase or exchange of real property, or
  memoranda  thereof,  and  instruments  canceling   or   extending   such
  contracts.  Each  set  must contain two lists in alphabetical order, one
  consisting of the names of the grantors  or  mortgagors  and  assignors,
  followed  by  the  names of their grantees, mortgagees or assignees, and
  the other list consisting of the names of the grantees or mortgagees and
  assignees, followed by the  names  of  their  grantors,  mortgagors,  or
  assignors,  with  proper  blanks  in each class of names, for subsequent
  entries, which entries must be made as  instruments  are  delivered  for
  record.  This  section,  so  far  as  relates  to the preparation of new
  indexes, shall not apply to a county where the recording officer now has
  general numerical indexes.
    A recording officer who records  a  conveyance  of  real  property  or
  assignment  of  rent,  sold  by virtue of an execution, or by a sheriff,
  referee or other person, pursuant to a  judgment,  the  granting  clause
  whereof  states  whose right, title or interest was sold, must insert in
  the proper index, under the head, "grantors" or "assignors", the name of
  the officer executing the conveyance, and of each  person  whose  right,
  title or interest is so stated to have been sold.
    Such  indexes  shall  form  a  part  of  the record of each instrument
  hereafter recorded.
    A  county  clerk  may  adopt   a   new   indexing   system   utilizing
  electro-mechanical, electronic or any other method he deems suitable for
  maintaining the indexes.