2xx series is for second class vehicles and 3xx for composite vehicles.
201-208 seem to be vehicles that were always second class. 209 upwards are vehicles that were originally composite, now downgraded to second class only. The exception to this rule is 220/1, these are gangwayed versions of ungangwayed 201/2.
DP 201
Class 116
DMS
Diagram BR 554
DP 202
Class 117
DMS
Diagram BR 535
DP 203
Class 119
DMS
Diagram BR 541
DP 204
Class 120
DMS
Diagram BR 586
DP 205
Class 120
DMS
Diagram BR 637
DP 206
Class 123
DMS
Diagram BR 574
DP 208
Class 126
DMS
Diagram BR 551
DP 209
Class 104
DMS
Diagram BR 558
DP 210
Class 101
DMS
Diagram BR 621
DP 211
Class 105
DMS
Diagram BR 529
DP 212
Class 101
DMS
Diagram BR 618
DP 213
Class 101
DMS
Diagram BR 619
DP 214
Class 101
DMS
Diagram BR 620
DP 215
Class 107
DMS
Diagram BR 649
DP 216
Class 101
DMS
Diagram BR 690
DP 217
Class 104
DMS
Diagram BR 580
DP 218
Class 104
DMS
Diagram BR 559
DP 219
Class 108
DMS
Diagram BR 544
DP 220
Class 116
DMS
Diagram BR 854c
DP 221
Class 117/118
DMS
Diagram BR 852
DP 226
Class 108
DMS
Diagram BR 609
DP 227
Class 108
DMS
Diagram BR 638
DP 301
Class 101
DMC
Diagram BR 618
DP 302
Class 101
DMC
Diagram BR 619
DP 303
Class 101
DMC
Diagram BR 620
DP 304
Class 101
DMC
Diagram BR 621
DP 305
Class 104
DMC
Diagram BR 558
DP 306
Class 104
DMC
Diagram BR 559
DP 307
Class 104
DMC
Diagram BR 580
DP 308
Class 105
DMC
Diagram BR 529
DP 310
Class 108
DMC
Diagram BR 544
DP 311
Class 108
DMC
Diagram BR 609
DP 312
Class 108
DMC
Diagram BR 638
DP 313
Class 110
DMC
Diagram BR 563
DP 314
Class 111
DMC
Diagram BR 616
DP 315
Class 111
DMC
Diagram BR 617
DP 316
Class 120
DMC
Diagram BR 577
DP 317
Class 101
DMC
Diagram BR 621