Specifies a list of additional files required to support the Linked Coded HTML file. These can be any files that are referenced by the linked HTML file, such as a graphic. Author-it copies all files specified to the publishing folder when publishing HTML based outputs. An error is displayed if any of these files cannot be found. Relative or fixed paths are supported.
The WebAdditionalFiles element corresponds to the "Specify any additional file required" field, on the "Linked HTML" sub-tab,on the HTML tab of the File object.