The class Segment_Delaunay_graph_vertex_base_2<Gt,SSTag> provides a model for the SegmentDelaunayGraphVertexBase_2 concept which is the vertex base required by the SegmentDelaunayGraphDataStructure_2 concept. The class Segment_Delaunay_graph_vertex_base_2<Gt,SSTag> has two template arguments, the first being the geometric traits of the segment Delaunay graph and should be a model of the concept SegmentDelaunayGraphTraits_2. The second template argument indicates whether or not to use the simple storage site that does not support intersecting segments, or the full storage site, that supports intersecting segments. The possible values are CGAL::Tag_true and CGAL::Tag_false. CGAL::Tag_true indicates that the full storage site is to be used, whereas CGAL::Tag_false indicates that the simple storage site is to be used.