OTS11 — transaction versus transaction context

The OTS spec makes a difference between transaction and transaction context:

Roughly:
transaction - an ACID unit of work
transaction context - information about a transaction associated with a thread

My understanding is that the OTS then also makes this distinction for
propagation, and I think this is where we disagree:
i) transaction propagation
ii) transaction context propagation

My understanding is that
i) explicit and implicit transaction propagation refer to the application
level: whether or not transactional behavior is specified in the operation
signature
ii) transaction context propagation refers to the ORB level

Thus the application can choose how it wants to control whether the transaction
is propagated. That's i). But once it is decided that a transaction has to be
propagated, the question is by what mechanism at the ORB level. That's ii).

Your understanding is that you can have only explicit or implicit and it refers
to both levels, right?