Re: [MMUSIC] AD Evaluation of draft-ietf-mmusic-rfc4566bis-32

Ben Campbell <> Mon, 11 March 2019 23:23 UTC

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From: Ben Campbell <>
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Date: Mon, 11 Mar 2019 19:22:35 -0400
Cc: Colin Perkins <>,
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To: Paul Kyzivat <>
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Subject: Re: [MMUSIC] AD Evaluation of draft-ietf-mmusic-rfc4566bis-32
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Sent from my iPhone

> On Mar 11, 2019, at 5:26 PM, Paul Kyzivat <> wrote:
> On 3/11/19 1:43 PM, Colin Perkins wrote:
>>>> §5 has several changes to normative language. Most are okay, but I think the change from “all MUST appear in exactly the order given here” to “all must appear” weakens it too much, and I’d prefer that to remain a MUST.
>>> The reason for changing that is because the *normative* specification of the ordering is from the ABNF. The text here is explanatory and non-normative. (Note that a couple of paragraphs prior to this is a new statement emphasizing that the ABNF is normative.)
>> Sorry, but I think this change is problematic. The text needs to use normative language that is consistent with the ABNF.
> My thinking is that we don't like to have redundant normative specification, just in case they aren't consistent. The ABNF is normative. This section is of necessity an approximation.
> But I defer to Ben or whoever.

I agree with both of you. :-) 

That is, we should avoid duplication normative requirements when possible, because it increases the chance of  spec errors. But we should still try to make sure the sections agree.

>>>> This is a normative requirement of RTP, however. If we want to avoid normative examples, which I’d agree makes sense, then this needs to be rewritten as just “An RTP-based system in recvonly mode SHOULD…”.
>>> That is the way it was. The change from "SHOULD" to "should" was to make it non-normative.
>>> Or were you requesting to remove “e.g."?
>> Remove the “e.g.”, yes, but also change “should” back to “SHOULD”.
> I thought the point was that the RTP specs are normative and this is only an example, and so shouldn't be normative.

I do not have the text in front of me, but I agree that examples should not be stated normatively.



>    Thanks,
>    Paul