Final Action vs. Date of Filing

[ash-ish]

What is the difference between final action data and date of filing for employment based applications? I read somewhere that the filing date is for people residing outside the US to file application to the visa center. The USCIS directs you to this link to determine if you can use the filing date or action date: https://www.uscis.gov/green-card/green-card-processes-and-procedures/visa-availability-priority-dates/adjustment-of-status-filing-charts-from-the-visa-bulletin

I am confused. Can some one enlighten me on this? Thanks.

[Mav777]

Google? This information is widely available online on multiple sites/forums.

FAD is when the Priority date is current and the i 485 will be processed. DOF is when you are allowed to file i485 but the application will remain pending until the priority date becomes current ie the FAD reaches the Priority date. Uscis sometimes allows the DOF to gage the demand for gc visas.