Topic: The audio of the GURU is? AC3 5.1 side in AAC

It is how much correct: to transcode EAC3/AC3 5.1 side in AAC LC 5.1? Simply in AAC there is no configuration 5.1 side ( to a measure I did not find it in the standard). Now I see that the people simply encode as AAC 5.1, and not . But how much it generally is correct? I understand that the result will be played, but the information on a configuration was lost. Where it can get out? Or can  is to specify a method a configuration 5.1 side for AAC?