I had assumed that bugs allowing such miscarriages of justice would require a completely unsound accounting method in the software. Unless, eg, the accounting

I had assumed that bugs allowing such miscarriages of justice would require a completely unsound accounting method in the software. Unless, eg, the accounting simply didn't store a transaction ledger and software didn't store logs, and instead mostly just updated balances with no history, it was unclear to me how software bugs in an otherwise reasonably sound accounting method could result in accounting so wrong that it couldn't seen to be incorrect when investigated at the level of thoroughness one might expect for court proceedings. But these bugs suggest that at least some of the errors would likely have been obvious in a ledger, and the Post Office simply didn't care. That rather makes Fujitsu look not quite as bad here, and the Post Office look worse.