External References in BricsCAD
Quick answer: An external reference attaches a pointer to an external drawing file rather than copying its entities in. The entities appear in your current drawing without actually being added to it, keeping file size small, and any changes to the original file automatically show up the next time you open the drawing referencing it.
Xrefs vs Inserting a Drawing as a Block
Insert a drawing as a block, and every entity from that separate drawing gets added directly into the current one; there’s no live link, and later changes to the original file have no effect on what you already inserted. Attach it as an external reference instead, and only a pointer gets added: the entities display, but aren’t actually stored in the current drawing, so attaching an Xref doesn’t meaningfully increase file size. Better still, edits to the original file automatically appear wherever it’s referenced, the next time that drawing opens, or immediately if you manually reload the Xref while working.
Why Use External References
- Assembling master drawings from separate component drawings.
- Coordinating work with others in a group.
- Keeping file sizes down while still working from the most recent version of a referenced drawing.
The External Reference Commands
| Command | What it does |
|---|---|
XREF |
Opens the Attachments panel |
-XREF |
Attaches and detaches DWG files via the Command line |
XATTACH |
Attaches an externally referenced drawing through a dialog box |
XCLIP |
Clips an externally referenced drawing’s display, adjusting front and rear clipping planes |
Note: this page’s own body text describes XREF as attaching DWG files “through the Drawing Explorer,” but that’s inconsistent with the command’s own listed description and with an earlier page in this hub, both of which describe XREF as opening the Attachments panel instead. The table above reflects that more consistent description.
Fading and Notification Settings
XDWGFADECTL controls how much external references fade on screen, accepting values from 0 (no fading) to 90; this only affects the screen display, not printing. XNOTIFYTIME sets how often BricsCAD checks for modified external resources, Xrefs, images, and PDF attachments, provided XREFNOTIFY, IMAGENOTIFY, and/or PDFNOTIFY are on. XREFNOTIFY itself controls whether warnings appear for missing or modified Xrefs at all.
Frequently Asked Questions
Does attaching an Xref significantly increase my drawing’s file size? No, only a pointer to the external file gets added, not the entities themselves, so file size stays largely unaffected.
If I edit the original drawing file, will drawings referencing it as an Xref update automatically? Yes, the next time you open a drawing containing that Xref, or immediately if you manually reload it while working.
Does XDWGFADECTL affect how external references print? No, it only affects the screen display, not printing.
What’s the difference between XREFNOTIFY and XNOTIFYTIME? XREFNOTIFY controls whether warnings for missing or modified Xrefs appear at all. XNOTIFYTIME sets how frequently BricsCAD checks for those modifications in the first place.