Within an xref or block you can define objects as boundary objects for spaces. These objects can be used to generate spaces in a host drawing.
In order to use boundary objects from an xref in a host drawing, the xref must have its Bound Spaces property set to Yes. (This is the default setting when inserting an xref.) If the xref’s Bound Spaces property is set to Yes, objects in it that have their Bound Spaces property set to Yes, too, will be used to generate spaces in the host drawing. If the Bound Spaces property of the xref has been set to No, any objects in the xref are ignored when generating spaces in the host drawing, regardless of whether they have their Bound Spaces property set to Yes.
Blocks work according to the same principle, except that the default setting for the Bound Spaces property of a block is dependent on the Bound Spaces properties of the objects inside the block. If none the objects inside the block has its Bound Spaces property set to Yes, then the block’s Bound Spaces property will be No. If there is at least one object inside the block that has its Bound Spaces property set to Yes, then the block’s Bound Spaces property will be set to Yes, too.
When blocks or external references are nested, and a block or external reference in the hierarchy has its Bound Spaces property set to No, then all blocks and external references nested in it are not used to bound spaces, even if some of the nested blocks or external references contain objects that have their Bound Spaces property set to Yes. In order to use boundary objects from nested blocks and xrefs, the containing level must have its Bound Spaces property set to Yes.
If a legacy drawing is opened in the latest AutoCAD Architecture 2025 toolset release, all blocks and external references that contain boundary objects will by default have their Bound Spaces property set to Yes.