I'm not sure yet, but my impression is that the "Single Source of Truth" was an append-only message-list, written periodically to write-only CD-ROM. This was di

I'm not sure yet, but my impression is that the "Single Source of Truth" was an append-only message-list, written periodically to write-only CD-ROM. This was difficult to query, so extracts were pulled down to an investigator's workstation, to be processed into spreadsheet format, that the prosecutors and auditors could consume. That conversion to spreadsheet-format was also unreliable, and required human intervention. So the data presented to the court wasn't the raw Single Source of Truth, but rather had been through a dodgy extraction process, in which human error was possible, and which resulted in Excel spreadsheets with hacked macros for "fixing" errors. Excel itself is not famous for it's reliability and trustworthiness as accounting software.