I am the assigned ART directorate reviewer for this document. These comments were written primarily for the benefit of the ART area directors.  Document editors and WG chairs should treat these comments just like any other last call comments.

This document extends the SUIT manifest format to support multiple trust domains. The document is ready, but contains some nits.

Nits.
1. Section 3 describes the changes in the SUIT workflow and, as a result, shows the expected resulting workflow. I'm puzzled why the resulting worflow ends on the "6. Install Payload(s)." step and doesn't include the next "5. Verify image(s)." step from the original workflow. I assume that authors included only affected part of the original workflow (i.e. those steps between which new steps are inserted), but this really confuses me. Unless I'm missing something, I suggest to provide the full new workflow.

2. Section 7. I fail to understand what "=" means in the text:  "This extension is backwards compatible when used with a Manifest Processor that supports the Update Procedure but = does not support the Staging Procedure and Installation Procedure...". I assume it is a typo.

3. Section 7 updates the Update Procedure defined in Section 8.4.6 of suite-manifest draft, but after reading both I have had a hard time to figure out how the procedure is modified. I understand that it is now divided into two sub-procedures, but the dividing line is not clear. I assume the first sub-procedure corresponds to the step 1 in the Section 8.4.6 of suite-manifest draft and the secont - to the rest of steps, but this is only my guess. I think that the draft can be more clear on this and be more close to the description of the Update Procedure from suite-manifest draft.