# PDFATTACH Command [GstarCAD 2027](Help%20System/GSTARCAD/2027/Index.md) → [Commands](Help%20System/GSTARCAD/2027/Commands/(Commands).md) → [P](Help%20System/GSTARCAD/2027/Commands/P/(P).md) ## Function Description: This command is used to insert a PDF file as an underlay into the current drawing. When you attach a PDF file as an underlay, you link that referenced file to the current drawing. Any changes to the referenced file are displayed in the current drawing when it is opened or reloaded. The Select Reference File dialog box is displayed. Once you select a PDF file, the [Attach PDF Underlay dialog box](Help%20System/GSTARCAD/2027/Commands/03%20Dialog%20Boxes/Attach%20PDF%20Underlay%20Dialog%20Box.md) is displayed. ## Command Access: > **Icon:**  > **Menu:** Insert > PDF Underlay > **Ribbon:** Insert > Reference > PDF Underlay > **Toolbar:** Insert > Insert a PDF Underlay > **Command:** PDFATTACH > **Alias:** / **Command Prompts: /**  **Related References：** - [Commands about Underlays (GstarCAD 2026)](../../../2026/Commands/00%20Command%20Groups/Commands%20about%20Underlays.md) **Related Tasks：** - [To Attach a DWF or DWFx Underlay (GstarCAD 2026)](../../../2026/Commands/01%20Procedures/To%20Attach%20a%20DWF%20or%20DWFx%20Underlay.md) - [To Attach a PDF Underlay (GstarCAD 2026)](../../../2026/Commands/01%20Procedures/To%20Attach%20a%20PDF%20Underlay.md) - [To Attach a DGN Underlay (GstarCAD 2026)](../../../2026/Commands/01%20Procedures/To%20Attach%20a%20DGN%20Underlay.md) - [To Detach an Underlay (GstarCAD 2026)](../../../2026/Commands/01%20Procedures/To%20Detach%20an%20Underlay.md) --- [Original help](https://www.gstarcad.net/help/GstarCAD_2027_en-US/detail/commandReferences/PDFATTACH.html) · © Gstarsoft Co., Ltd.