RE: T2 Clarify TimeToLive

Currently TimeToLive is defined in section 8.4.6.4 as ...

The TimeToLive element indicates the time by which a message should be
delivered to and processed by the To Party.

... and in section 10.2.3 as ...

The TimeToLive value indicates the time by which a message should be
delivered to and processed by the To Party.

What I think you are suggesting is that we provide guidance on how it should
be set. There are two factors which can affect this:
1. Setting it to a value long enough so that it is longer that the time
required to do all the retries on all the hops between the From and To
Parties. By definition this is not precisely computable.
2. Setting it to a value that makes sense in a business context, e.g. if
this PO gets there in a day then it is fine.

I think adding this to the spec as a non-normative note is a good idea.

David