The Regulation 37 (formally 35 and 33) Special Areas of Conservation (SAC) feature maps provide the indicative baseline extent and status (i.e. "Definite" or "Potential" feature status and / or confidence) of SAC features at the time of site designation. These are the maps that should be used to assess potential impacts of plans and projects and for casework advice. They also form the baseline against which we measure changes in extent during Habitats Directive reporting.