Aux [1..6] Mix on Atem Constellation

I have been tinkering around with the API for a Constellation HD switcher and the IBMDSwitcherAudioRoutingSourceIterator gives me six "Aux Mix" inputs (see attachment). What are these? The number six suggests that it is somehow related to the six SDI outputs of the switcher, but why is is called "Mix"? Furthermore, the IBMDSwitcherFairlightAudioAuxOutputIterator only yields four inputs which match what the ATEM software control shows in the audio mixer. Is there any way to actually create a "mix" for these six routing sources?

Thanks in advance,
Christoph