The blocks can be used in backward migration to other AutoCAD programs, or to create objects that represent the spatial location of specified civil points in the active drawing.
You can select the points to include in the block using both the Spatial Filter and Point Group options. For example, under Spatial Filter you could select the Current Display and under Point Groups you could also include a specified point group.
The option Use Existing Block is only available if the block contains at least three attribute definitions with the exact names ELEV, POINT, and DESC. If there are no blocks in the drawing with these exact attribute definitions, this option is not available. Then you must use the Make New Block option.