As I wrote a while back it is always a good idea to get important agreements in writing – Today I just had to remind myself that – especially in these days of electronic communication – there is always the option to put it writing yourself.
As a last resort – e.g. if an official protocol would be taken as an offense – I take the tangential approach as in “When we agreed on we also mentioned – would it be OK for you to treat these separately?” thus getting a written – and circulated – record of without offending my negotiation partner.
I most cases though it should be quite OK just to communicate openly and agree on putting the agreements in writing just to make sure that there are no misunderstandings.