Glossary/Drawing basics
DWG
AutoCAD's native binary file format for a single drawing.
DWG is the proprietary file format AutoCAD (and Plant3D, which is built on top of AutoCAD) saves drawings in. A single .dwg file can contain model geometry, one or more layouts, blocks, layers, text styles and — in Plant3D — piping and equipment asset data.
Because the format is binary and version-specific, most automation has to go through AutoCAD's own engine (or a compatible one) rather than parsing the file directly — which is why every CADXChange tool runs alongside a licensed copy of AutoCAD instead of reading .dwg files on its own.