Amending Chapter 19-3900 of The Philadelphia Code, entitled "Tax Exemptions for Longtime Owner-Occupants of Residential Properties," by clarifying that once the "deemed certified market value" is set for purposes of the Longtime Owner Occupants Program ("LOOP"), it shall remain at that value regardless of whether the property is subsequently assessed at a certified market value that is higher or lower than the certified market value that was originally used to calculate the "deemed certified market value"; and by authorizing eligible taxpayers who have obtained the LOOP tax exemption to opt ou — Open Common Ground