the locomotive with the class. SNCF's adaptations included using the axle arrangement in full, and reversing the class letters of tank locomotives. For example, the SNCF used 040.A., and 242.TA. where the PLM used 4.A., and 242.AT. Class letters A-N were used for existing designs, letters P onwards for SNCF designs. Others railways' designs taken over after World War II were usually given the letter U (American), W (British), X, Y, or Z (German). Where locomotives were upgraded or rebuilt, the class letter changed, but not the number. While the Region Nord renumbered all their classes from 1, the remaining 4 regions re-used the last three digits of the old number in the new number. As there were more classes that available letters of the alphabet, the axle arrangement was prefixed with a digit indicating the owning region: 1 Est (former Est and AL lines), 2 Nord 3 Ouest (former État lines) 4 Sud-Ouest (former Paris-Orleans and Midi lines) 5 Sud-Est (former PLM lines). Region 5 was later split in two, with the southern part becoming 6 Mediterranée Locomotives transferred from one region to another could change their class letter and numeric suffix. 1. Est 021.A, ex Est 441 to 485 220.A, ex Est 2401 to 2432 141.TB, ex Est 4401 to 4512 141.TC, ex Est 141.701 to 141.742 2. Nord 231.C, ex Nord 3.1201 to 3.1290 040.TG, ex Nord 4.2016 to 4.2095 141.TC, ex Nord 4.1201 to 4.1272 150.B, ex Nord 5.1201 to 5.1230 3. État 040.TA, ex État 40-001 to 40-143 141.TC, ex État 42-001 to 42-020 141.TD, ex État 42-101 to 42-140 140.C, ex État 140-101 to 140-370 141.B and 141.C, ex État 141-001 to 141-250 230.B, ex État 230-001 to 230-055, ex État 3701 to 3755 230.J and 230.L, ex État 230-781 to 230-800 231.B, ex État 231-011 to 231-060 231.C/D/E/F/G/H/J, ex État 231-501 to 231-783 231.997, ex État 231-997 to 231-999, ex Württemberg C 4. PO-Midi 040.TA, ex Midi 040.421 to 040.421, ex Midi 421 to 424 141.TA, ex PO 141.301 to 141.490, ex PO 5301 to 5490 141.TB, ex PO 141.616 to 141. 740, ex PO 5616 to 5740 240.TA, ex Midi 240.501 to 240.518, ex Midi 4501 to 4518 5. PLM 020.TA, ex PLM 7001 to 7005 030.TA, ex PLM 3.AT 030.TB, ex PLM 3.AM, rebuilt from PLM Bourbonnais 130.TA, ex PLM 130.AT, ex Prussian T9.3 130.TB, ex PLM 130.BT, ex Prussian T11