.bc3 is Fiebdc format
Key Features: .BC3 File Extension
What is an .BC3 file?
The bc3 file extension is used for files in a standard exchange format for construction databases defined by FIEBDC association.
The latest version of this format is from July 7, 2008.
This bc3 file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.