This dataset is based on a legacy system that is no longer maintained by the NYC Department of Sanitation (DSNY). It contains information about the cleaning requests associated with different vacant lots.
Some current data related to vacant lots can be found in the 311 Service Requests dataset at (https://data.cityofnewyork.us/Social-Services/311-Service-Requests-from-2010-to-Present/erm2-nwe9), and filtering the "Complaint Type" field for "Vacant Lot".