Protocol must be also extendible. One set is going to be specified. The first version of the protocol should define a way to expand the protocol. It is not an exhausted list. Perhaps the reality is that now in 2000 we do not need this for the first version.
Discussion is encouraged in the mailing list.
The first version should be something realistic for most of the people. Exactness is for example 3 inc. Protocol only delivers accuracy. Exactness can be used for multiple replies, but accuracy is different for different clients. This can be discussed more in the list since exactness is internal parameter while accuracy is external.