The <host:port> section of the form submission xml link must be changed in the Doc URI wizard to "frevvo://" to take advantage of this change. Refer to the example in the Initializing Forms with XML Documents topic for the details.
Existing upload controls on existing forms will behave as they always have after this change is made. This is true as long as the configuration relative to this feature is not changed by the designer. In other words the default configuration for this feature will cause the system to use the uploaded file's name as the attachment name as it always has.
Legacy submissions with attachments will not have 'origFileName' in their contentTypes, so need to set the re-directed attachment name (that is used for the save as name) to the filename from the content type (if origFileName is not present).
Migration Considerations for Live Forms In-house Customers