This User Guide contains information about the ONSPD including: directory content; data currency; the methodology for assigning areas to postcodes; data formats; data quality and limitations and details of recent changes that have impacted on the data. Various annexes and tables provide more detailed supporting information. (File size - 487 KB) STOP PRESS For the new release of the ONSPD, there are important field changes. Please read the User Guide for full details. The ‘old’ directories will be included for one release only. From May 2018 only the new layout will be available.