ATTACH command, insert drawing and raster image in dwg, dwf, pdf, dgn format
The ATTACH command is used to insert external reference, raster image or underlay (DWF, DWFx, PDF or DGN file) to current drawing.
Command
ATTACH
Ribbon: Insert > Reference > Attach
Function Description:
In the "Select Reference File" dialog box, users could select one file to attach in current drawing.