Re: [Lsr] When is an IANA Registry Required

Tony Li <> Wed, 17 March 2021 20:56 UTC

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Date: Wed, 17 Mar 2021 13:56:06 -0700
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Cc: Alvaro Retana <>, "" <>, "" <>, John Scudder <>, Christian Hopps <>, "" <>
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Subject: Re: [Lsr] When is an IANA Registry Required
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> [Les:] The question here is whether there is a qualitative difference between two classes of bit fields.

That is indeed the key question. IMHO, there is not.

I don’t much care if a field is updated by a bis document or a related document. Regardless of the cause, as soon as there is more than one source of truth about the field, we are
creating ambiguity and confusion.  

At the same time, I see no point in a registry with contents that never change. Thus, I will propose an alternative: by analogy to copy-on-write shared memory semantics, I propose that
we apply ‘registry-on-write’ semantics. 

Specifics: When a potentially shared field is created, the defining document speciifies the name of a future registry, but does NOT request IANA create the registry at this time. When any document wishes
to update the field, it requests that IANA create it and populate it with both legacy and updated values.

Implementors that come along either document know where the source of truth is.  If the registry has not been created, then there is no ambiguity. If it has been, then there is no ambiguity.