"- it can be audited as easily as any custodian"

You mean proof of liabilities? I remember hear you on parallelni polis during the pizza day a couple of years ago about this; its already a reality? 

 Proof of liabilities is what makes it *better* (i.e. publicly) to audit than a normal custodian.  

 But its what you mean with
"- it can be audited as easily as any custodian"?
Trying to understand the underlying concept  

 Auditing with custodial systems typically meant that you get an "expert" and show them your database and they say "ok". You can do the same with ecash and much more than that. 

 A ok, I see. But there's an idea around audits to make them more accessible/transparent, or its like, me as a mint, I could invite a choosen auditor to decide if my mint is okay or not okay? 

 Yes, there is an idea on the horizon and it will require some work but it's possible:

https://gist.github.com/callebtc/ed5228d1d8cbaade0104db5d1cf63939