AutoCAD External References (Xrefs)

Use this skill when working with external reference drawings — attaching, overlaying, binding, detaching, reloading, or analyzing xref dependencies in an AutoCAD drawing.

Attachment vs Overlay

AutoCAD supports two xref modes:

• Attachment — the xref and all its nested xrefs propagate into any drawing that references the host. Use for shared base files (survey, utilities) that should always travel with the drawing.
• Overlay — the xref appears only in the immediate host drawing. Nested overlays are ignored by parent drawings. Use to avoid circular references or to keep coordination views local.

The mode is stored on the BlockTableRecord and can be changed after the fact by toggling IsFromOverlayReference.

Attaching Xrefs

Attach (Standard Attachment)