You can assign a WEDD Signature to associate a structure file to a data file. This will only allow a data file WEDD Signature to be opened by a structure file with the same WEDD Signature. In 4D 2004, you can assign a WEDD Signature to the structure file and data file through the Data Management of the database preferences. To remove the WEDD Signature, you simply delete the contents of the WEDD Signature field in the Data Management interface.