Using XREFs in Round-Trip Communication

In this scenario, you are assigned to work on one part of a larger project. You get the whole project (or the part of it relevant to your job), extend it with your part and send it back. In this case we recommend that you use the XREF (External Reference) model. Using this model you can see all parts of the project, but modify only the part assigned to you.
The XREF model is based on a “master” AutoCAD file containing general information (e.g. a site map).
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First, attach this “master” file as an XREF to your ARCHICAD plan to see the current state of the project.
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Detail plans, including your file, are added as XREF’s. Make your modifications in your external file, using ARCHICAD. You will be able to modify only your file.
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Meanwhile, other members of the project team are working on their files in parallel. To receive the changes made by the others, reload the “master” file. The updated file contains all the modifications submitted by the other parties.
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If you want the others to see the work you have done so far, you can send your changes by exporting your work in AutoCAD format.
The XREF model preserves the “master” AutoCAD file: each team member works only on his/her own part without being able to modify others’ work, because externally referenced files don’t have to be sent back to their original sources.
Due to essential differences between ARCHICAD and AutoCAD, perfect round-trips are not possible. (For example, if you import and then export something, polylines and structures are lost.) In practice, however, you can rely on the suggested XREFs, which do not involve overwriting the other party’s original file, so that you don’t need to rely on a perfect round-trip. If you work in round-trip communication, your file never gets overwritten. The specialist gets new DXF/DWG files from you from time to time, which contain imperfect reproductions of his modifications. You can avoid these imperfections if you keep his additions in a separate XREF file, attached as an external reference to the file you send back to him.