Studying further I discover this:
Column 1 - Ground-attack / anti-tank payload.
Column 2 - Anti-bomber (for fighters only) - either heavy cannon, extra ammo, rockets payload.
Column 3 - Level bombing or armed recon payload (against bridges/factories/stations, etc).
Column 4 – Long-Range payload (Fighter Only) – Fuel drop tanks are added if the mission distance is 200km or greater. DCG removes drop tanks from CAP flights where the maximum action radius is less than 400 kilometers.
Column 5 – Anti-ship payload.
Column 6 - still unknown (maybe a bomber escort loadout because in 3.50 payload.dcg it is used only by P-47 and P-51)
(if payloads is set to "none" this will prohibit any assignment of that kind of missions.)
Related timetable commands
Column 1 - Date NewPayload Aircraft GAWeapon =
Column 2 - Date NewPayload Aircraft AAWeapon =
Column 3 - Date NewPayload Aircraft LBWeapon =
Column 4 - Date NewPayload Aircraft Droptank =
Column 5 - Date NewPayload Aircraft ASWeapon =
Column 6 - Date NewPayload Aircraft (unknown to me atm)
EXAMPLE from timetable:
19410810 NewPayload JU_88A4 GAWeapon = 2xSC1000
19410810 NewPayload FW_190A8 AAWeapon = r14mg15120
19410810 NewPayload JU_88A4 LBWeapon = 10xSC50
19410810 NewPayload FW_190A6 Droptank = r11tank
19410810 NewPayload JU_88A4 ASWeapon = 2xSC1000
19410810 NewPayload JU_88A4 (code unknown) =