Designations such as strategic gaps, rural buffers and green wedges were first referred to in UK planning guidance The Countryside in 1997. The guidance states that in reviewing development plans local authorities should re-assess the function and justification of such policies, at the same time recognising that they can contribute to urban form and the shaping of urban areas. Strategic gaps are to protect the setting and separate identity of settlements, and to avoid coalescence; retain the existing settlement pattern by maintaining the openness of the land; and retain the physical and psychological benefits of having open land near to where people live. Rural buffers are to avoid coalescence with settlements (including villages) near a town until the long-term direction of growth is decided. Green wedges are to protect strategic open land helping to shape urban growth as it progresses; to preserve and enhance links between urban areas and the countryside; and to facilitate the positive management of land.