[Moims-dai] [EXTERNAL] RE: CESG conditions on your OAIS Reference Model, CCSDS 650.0-P-2.0

Shames, Peter M (US 312B) peter.m.shames at jpl.nasa.gov
Tue Aug 18 17:56:22 UTC 2020

Dear David, et al,

I'd like to thank you and your team for taking my suggestions seriously and for working diligently to improve the clarity of the document.  I am really glad that you took this opportunity to make these long overdue changes.  I suspect that your community will also appreciate the changes.

I have read the document (a quick skim this time), and find that I agree with all of the changes that you have made.  The added clarity in use of terms and diagrams helps a lot.  I did find a few relatively minor items that I still wish to ask that you fix.  Instead of doing the usual "change this to that" PID format I just made the proposed changes directly in the text, which I have attached with Track Changes turned on.  For transparency, I will tell you where to look:

Sec 1.1: fixed the definition of an OAIS to align with the usual notion of what a "system" is:

An OAIS is an Archive system consisting of hardware, software, and procedures developed and operated by an organization.  The organization has accepted the responsibility to preserve information and make it available for a Designated Community. The organization may be part of a larger organization.

Made the same change in sec 1.6.2 Terminology.

In other sections and sub-sections I added a clarifying sentences in the intro paragraphs, of the general form: "This sub-section (or this entire section) is non-normative.".  I am concerned that without this sort of clarity the mix of normative and non-normative materials in various sections can cause confusion.  I did not want it to be too intrusive, but I think we must be clear.

To take the "sting" out of this, in some sections I added an explanatory sentence, like this one in Sec 4.2:

This entire subsection is informative, but provides useful abstractions for understanding how an OAIS might be designed.

I hope that you and your team can accept these changes.  If the answer is yes you have my concurrence to go forward.

Thanks, Peter

From: David Giaretta <david at giaretta.org>
Date: Tuesday, August 18, 2020 at 9:07 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov>
Cc: MOIMS-DAI List <moims-dai at mailman.ccsds.org>
Subject: Re: [Moims-dai] [EXTERNAL] RE: CESG conditions on your OAIS Reference Model, CCSDS 650.0-P-2.0

Dear Peter

Steve Hughes provided us with feedback following your discussion with him. As a result we have taken an in-depth look at the conformance sections, the definitions and discussion of Representation Information, and in particular “Semantic Information”, and the discussion of Representation Information Networks. I believe we have made significant improvements to OAIS as a result. Some of the  text dates back to the original version of OAIS; it is only thanks to your insistence that we were forced to recognize a number of weaknesses and sources of confusion for readers.

The updated document is available at https://cwe.ccsds.org/moims/docs/MOIMS-DAI/Draft%20Documents/OAIS%20v3/650x0020_CESG_Aproval_Mod-20200818.doc?Web=0

A short list of the changes are:
-          The conformance section 1.4 has been clarified as you suggested and the individual sections are clearly marked as “normative”
-          We checked the use of shall/must. One instance of “must” was missing from a section marked as normative. We found we did have some uses of “must” in informative sections, which we re-phrased.
-          Changed the name of Semantic Information to “Semantic Representation Information” to avoid confusion with Semantic networks etc.  The definition has been clarified to
o   “Semantic Representation Information: The Representation Information that further describes the meaning of the Data Object, and its parts or elements, beyond that provided by the Structure Representation Information.”
-          There is a similar change for Structure Information to “Structure Representation Information”, which is now defined as
o   “Structure Representation Information: The Representation Information that imparts information about the arrangement of and the organization of the parts or elements of the Data Object”
-          The explanation of Representation Information Networks has been updated, with some new diagrams which we hope make the concept very clear.

We hope that clears the way for progressing OAIS to the next stage.



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