Change:
6. <ins> An entity in the RATS architecture includes at least one of the roles defined in this document.  As a result, the entity can participate as a constituent of the RATS architecture.  Additionally, an entity can aggregate more than one role into itself.  These collapsed roles combine the duties of multiple roles.  In these cases, interaction between these roles do not necessarily use the Internet Protocol. They can be using a loopback device or other IP-based communication between separate environments, but they do not have to.  Alternative channels to convey conceptual messages include function calls, sockets, GPIO interfaces, local busses, or hypervisor calls.  This type of conveyance is typically found in Composite Devices.  Most importantly, these conveyance methods are out-of-scope of RATS, but they are presumed to exist in order to convey conceptual messages appropriately between roles. For example, an entity that both connects to a wide-area network and to a system bus is taking on both the Attester and Verifier roles. As a system bus entity, a Verifier consumes Evidence from other devices connected to the system bus that implement Attester roles. As a wide-area network connected entity, it may implement an Attester role.  The entity, as a system bus Verifier, may choose to fully isolate its role as a wide-area network Attester. In essence, an entity that combines more than one role also creates and consumes the corresponding conceptual messages as defined in this document. 7. </ins> The scope of this document is scenarios for which a Relying Party trusts a Verifier that can appraise the trustworthiness of information about an Attester.  Such trust might come by the Relying

Discussion:
added 4.4 "Roles and Entities", also removed the last occurrence of the artifact "role composition", and retained section 4.3 as is and added the usage scenario from issue
The introduction section uses the phrase "role compositions and data flows" then mentions "Passport Model" as an example of a role composition. In section 4.3 on Composite Device the second to last section describes "combinations of roles" using an example involving a Composite Device. I think the architecture should have crisper understanding of two concepts a) "topological models" (as defined by the section 5 heading that describes Passport, BKC and Hybrid; b) "role composition" which ought to refer to the "combining of roles" by a given entity. The terms "role composition" and "combining of roles" are too similar for them to have different meanings and "role composition" as an alias for "topological models" is unnecessary. I suggest pulling the second to the last paragraph in section 4.3 into a new section 4.4 titled "Role Composition" that has a paragraph defining role composition conceptually followed by the paragraph taken from section 4.3. Suggested Text for section 4.4: RATS roles are implemented by entities (e.g., devices). A simple realization of the architecture associates a single role to a single entity; for example, the topological models described in section 5.1 and 5.2 follow this convention. However, entities may host multiple roles as a way to accommodate more sophisticated use cases and deployment scenarios. An entity that both connects to a wide-area network and to a system bus may play both Attester and Verifier roles. As a system bus entity, a Verifier consumes Evidence from other devices connected to the system bus that implement an Attester role. As a wide-area network connected entity, it may implement an Attester role. The entity, as a system bus Verifier, may choose to fully isolate its role as a wide-area network Attester. Alternatively, attestation results might reflect an aggregation of system bus operational state claims in the form of Evidence. For example, in the Composite Device scenario, the lead Attester... Additionally, the introduction section should change "role composition" terminology to "topological models" as it references Passport.

"Role Composition" will be worked out of document.
Also addressed in Issue55. I recommend closing this issue.
"role composition" no longer appears in the doc. I agree this can be closed.
Taking into account the recent trends in terminology used in draft text & PR, I am proposing to add Entity and Sub-Entity to the terminology section. We do not need to over-specify here. Hence, only mentioning Composite Device and Components as an examplew for each of the terms in the definition text could be enough. Are there any objections to this proposal? If not, we could create a PR and address it in next week's meeting.
Agree so long as it is understood that other words can be used in place of entity when they add context for readability such as component, sub-component, device, environment and so forth.
This now relates to the comments on