PDFATTACH command 

The PDFATTACH command is used to reuse that PDF data in your own GstarCAD drawing files

Command Access :

Command Entry :PDFATTACH

Menu : Insert>Reference>PDF Underlay

If you receive project drawings in the form of a PDF file, you can reuse that PDF data in your own GstarCAD drawing files. For example, imagine that you are a landscape designer and you receive a PDF file for this building project. This particular sheet includes a floor plan that you want to use as starting point for your landscape design.