A chair I understand as a deliverable, but isn't a message just information?
For purposes of the mapping technique we can think of organized and packaged information as a deliverable. For example, let's take the bit of information that "Your order has been received."
The "packaging" or delivery mechanism for that message might be in the form of a document, an e-mail message - or oral or spoken, maybe even non-verbal such as a nod of the head.
Even though a spoken confirmation might be non-physical, there is still a basic nature of the content of that message - that of "order confirmation." "Order confirmation" then is the deliverable.
But what if you have something that isn't either of these - like a service?
The same principle would apply to a service such as a massage or a haircut. There is still a basic nature of that service that can be described as a deliverable. Again be specific. It is not just a service, it is a particular kind of service such as "inquiry response," "reservation" "tax preparation," "massage," etc.
Doesn't it get confusing calling all these different things deliverables?
It is actually far less confusing in practice than one would expect. It is quite different from a "task" perspective or process mapping which tends to define events, not deliverables.