N.Y. Comp. Codes R. & Regs. tit. 20, § 8189.11 – Lot subdivision.

(a) When land parcels are subdivided after the initial numbering, the new land parcels shall carry the original lot number and a suffix starting with the number one. A total of three unique numbers to the right of the decimal may be suffixed to the original lot number. Where an original land parcel is extensively altered, it will be necessary to renumber the land parcels. A new coordinate locator number, which shall not duplicate any previous coordinate locator number used, shall be assigned to each new land parcel. Where a land parcel falls on more than one map sheet, the map sheet containing the major portion of the land parcel shall show the assigned lot number and there shall be sufficient cross-reference between the adjoining portions to that land parcel.
(b) The description of lots in a subdivision may not be changed or altered to indicate the abandonment of a subdivision unless an instrument abandoning that subdivision has been filed with the appropriate assessor and recording officer. The instrument abandoning a subdivision shall include the following information:
1. (1) signed statements by the county treasurer and collecting officers of any city, town or village in which the subdivision is located that all taxes levied against the lots contained in the abandonment have been paid;
2. (2) the receipt of the clerks of those municipalities that the instrument has been filed with them; and
3. (3) if the subdivision is within a forest preserve county, the consent of ORPTS as evidenced by an endorsement pursuant to section 2375.3 of this Title.