C++
AcDbObjectId xrefBlockId() const;
Description
This function returns the object ID of the AcDbBlockTableRecord which refers to this database as an xref.
When an xref is reloaded by any means (for example, by the XREF Reload or XREF Path commands), the former database is kept in memory for Undo. This means that more than one database may point to the same xref block table record. However, only one may be the currently active xref database for that record. The database pointer returned by the AcDbBlockTableRecord::xrefDatabase() function on the found record is the active database for that xref.