The Nominal Roll of POWs published in 1945 by HMSO is the most accessible record of prisoners, but it should be used with caution. Although its has the note “All lists corrected generally up to 30 March 1945”, it mostly describes the situation in the autumn of 1944.
Discrepancies were caused by delays and confusion in records from Germany reaching the UK. In some cases records did not keep up to date with transfers between camps. Transfers were not uncommon and most of the POWs from 1940 experienced four or five camps before the end of the War.
For Oflag IX A/H my lists have to use the HMSO publication and what individual records survive, but for IX A/Z there is a nominal roll dated January 1945 and which forms part of the papers of the Senior British Officer, Lt-Col Kennedy, which are in the Imperial War Museum.