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

david at giaretta.org david at giaretta.org
Tue Aug 18 16:07:34 UTC 2020

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


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 

*	"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 

*	"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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