Section 5.1.2 cryptically states that OPES intermediaries cannot be
transparent. I would propose we explain the requirement, with the existing
statement as the way of satisfying the requirement. How about something
like:
It is a goal to not require the OPES client to explicitly request the
services of an OPES Intermediary. That is, most the operation of OPES
Intermediaries are transparent to the OPES client. Even though, under
normal use, the operation is transparent, the presence of OPES
Intermediaries MUST NOT be hidden from the user or the client (i.e., a
content consumer).
For example, the OPES client may request an object from a given URI. The
URI may resolve to an OPES Intermediary, rather than the content provider.
Both the OPES client and content provider must be aware of the OPES
Intermediary. In this regard, the client and the content provider MUST be
able to explicitly address the OPES Intermediaries at the IP layer.
Conversely, an OPES Intermediary MUST NOT share or proxy for the IP address
of an OPES client or content provider.