Regarding U.S. patent law under the Leahy-Smith America Invents Act, I'm wondering how the phrase actual filing date is defined (37 CFR §1.109). What value does the USPTO use as the official actual filing date?
For example, is actual filing date defined to be the date that appears on the patent application paperwork? This seems unlikely because the date on the application paperwork could be just about anything—e.g., a typo that yields an application date that is far into the future: the year 2021 is incorrectly specified as 2201.
Or is the actual filing date defined via a date stamp (or timestamp) that the USPTO affixes onto the application paperwork, or a timestamp that is entered into a computer database record that's associated with the application paperwork, after the application paperwork arrives at the USPTO?