The error codes are divided between 'User Interface Error Messages' and 'Command-Line Interface Error Messages'. User interface messages are understandable enough... You perform a P2V and the job errors out with an error message in the Admin Console. Command-Line, or CLI messages are those that appear in a PowerShell console when running scripts or performing interactive work.
User Interface Messages: http://technet.microsoft.com/en-us/library/dd548298.aspx
Command-Line Messages: http://technet.microsoft.com/en-us/library/dd548296.aspx