Re: empty lists, was: Benjamin Kaduk's Discuss on draft-ietf-httpbis-header-structure-18: (with DISCUSS and COMMENT)

Mark Nottingham <> Tue, 19 May 2020 12:24 UTC

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From: Mark Nottingham <>
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Date: Tue, 19 May 2020 22:20:43 +1000
Cc: Benjamin Kaduk <>, The IESG <>,,, HTTP Working Group <>, Tommy Pauly <>
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To: "Julian F. Reschke" <>
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Subject: Re: empty lists, was: Benjamin Kaduk's Discuss on draft-ietf-httpbis-header-structure-18: (with DISCUSS and COMMENT)
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On 19 May 2020, at 8:04 pm, Julian Reschke <> wrote:
> It really doesn't help a lot with the case of:
>  Foo:
> What's the point in disallowing this in the ABNF (and on the wire) when
> the normative parsing algorithm will accept it?

As has been said many times, the ABNF in the specification is not normative; it's illustrative. The proposed edit clarifies that. If that's still felt to be confusing, the right thing to do would be to remove ABNF from the spec completely, to avoid the confusion. I'm happy to do that if the IESG wishes so.

Julian, you've had many opportunities to bring this up before (having participated in the original issue about empty lists). It would have been much more helpful if you'd expressed your concerns earlier -- even during WGLC -- instead of after IETF LC. 


Mark Nottingham