Single selection mode makes it possible to select individual objects from a group. This applies to grouped plant symbols, areas with leader etc. Use this mode to adjust placement of leaders on areas made with Land Use Disposal or to adjust single elements in groups of for example plant symbols.
Single selection mode set the AutoCAD system variable PICSTYLE to '0'. The PICKSTYLE system variable controls selection of grouped objects and associative hatch patterns and their boundaries. The PICKSTYLE default setting is 1. The function Multiple Selection Mode will restore the setting.