How to Use Xrefs in BricsCAD BIM

Quick answer: External references (Xrefs) insert a model into the current BIM model without copying it, saving only a reference to the source model in the master. Multiple models attach without significantly increasing file size, and source models can be edited simultaneously by different team members, with the master always updatable to show each source’s latest version. XDWGFADECTL fades Xref display relative to entities in the current drawing (0, no fading, to 90), confirming the same variable covered on this hub’s general Xrefs pages earlier in this session. This is also the sixth page in this hub whose title reads “BricsCAD Lite & Pro” while filed under BIM, though it has a genuine BIM-specific addition worth keeping distinct: BIM XReference classification.

The External References Section

Open the Drawing Explorer and click External References for the Xref preview pane:

• Attach XRef: attaches a model as an external reference.
• Detach XRef: removes the selected Xref completely from the model.
• Reload XRef: reloads it, useful once the source model has changed and you want the master updated.
• Unload XRef: hides it from view without removing it.
• Bind XRef: permanently merges the source model into the current drawing, becoming part of it; its reference disappears from the Drawing Explorer.
• Insert XRef: converts Xrefs into blocks.
• Open XRef: opens the referenced drawing.
• Detail view / Icon view / Tree view: three ways to display the Xref list, the last showing relationships between Xrefs as a tree.

Attaching an Xref

1. Click Attach XRef in the Drawing Explorer; the Select Reference File dialog opens.
2. Choose the DWG file to attach and click Open; the Attach External Reference dialog opens.
3. Set your options and click OK:
   • Path field: shows the selected drawing’s full path.
   • Path type: Full path, Relative path, or No path. Full path breaks if you move the drawing containing the Xref, since BricsCAD keeps searching the old location. Relative path recreates the same folder structure at the new location, so it keeps working after a move.
   • External Reference type: Attachment includes every nested Xref too (a first-level Xref X containing nested Xrefs Y and Z brings all three in). Overlay attaches only the first level, leaving nested Xrefs unloaded, useful for preventing circular references.
   • Insertion Point: specify on screen or via X, Y, Z fields.
   • Scale: specify on screen or via X, Y, Z fields (tick Uniform Scale to control all three from the X field).
   • Rotation: specify on screen or via the Angle field.

Classifying an Xref as BIM XReference

The BIM XReference option of BIMCLASSIFY classifies a model as an external reference. This resolves the important warning covered on this hub’s IFC import and export page: this classification’s identification information isn’t explicitly represented in the current model or project database, it only appears once that model is attached to another project, following the attaching procedure above. Once attached, the BIM category shows up in the Properties panel for the classified model.

Detaching an Xref

Select the Xref (hold Ctrl to select or deselect multiple) and click Detach XRef in the Drawing Explorer.

Unloading and Reloading an Xref

Either click the Load column checkbox of a loaded Xref to unload it, then check it again to reload it, or select the Xref and click Unload XRef on the Details toolbar, then select it again and click Reload XRef.

Modifying an Xref’s Attachment Type and Paths

Click the Type column of an Xref to switch between Attach and Overlay. The same click-to-edit process works for modifying an Xref’s Saved path, or an overlay’s Found path. Click the X to close the Drawing Explorer; your changes take effect once it’s closed.

Frequently Asked Questions

What’s the difference between unloading and detaching an Xref? Unloading just hides it from view without removing it, and it can be reloaded; detaching removes it from the model completely.

How do I prevent circular references between Xrefs? Use the Overlay reference type, which only attaches the first level and leaves nested Xrefs unloaded.

When does a BIM XReference classification’s identification information actually become visible? Only once the classified model is attached to another project, it isn’t represented in the current model or project database beforehand.

What’s the difference between Full path and Relative path for an Xref? Full path breaks if you move the drawing, since BricsCAD keeps looking in the original location. Relative path recreates the same folder structure at the new location, so the Xref keeps resolving correctly.