Vector layers, or vector segments, are used to hold a set of related vectors. Vectors can be points, polylines (arcs), whole polygons, topological polygons, or objects without vertices which are really just database records.
Each vector object in GDB is called a Shape. Each Shape has a numeric identifier called a ShapeId that is unique within the layer, and is greater than or equal to zero. While the ShapeIds are normally assigned sequentially starting at zero, it is possible to have a layer with holes between ShapeIds.
Each Shape has a record of attributes associated with it. The attributes are stored in the layer, and are considered to be part of the shape. Each shape also has a list of zero or more vertices. Within GDB the vertices are represented using double precision IEEE floating point numbers; each vertex has an X, Y, and Z value. The vertices are presumed to be coordinates in the georeferencing system of the vectors.
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