What are advanced fields at Djongo?

[e-orlov]

I'm looking for pre-sale support.

To decide, which commercial package to buy, I need a descriptipon fo what certainly are Djongo's advaced fields. Documentation search doesn't answer this question.

Djongo's contact form seems to be broken, as it doesn't allow submitting a form.

Maybe this happens only to unregistered users - but its complicated, to buy a product, without knowing answers to pre-sale questions.