Subject: [quicwg/base-drafts] Identifier of the form "31 * N + 27" (#4294)

From: Lars Eggert <[email-masked]>
Date: Wed, 28 Oct 2020 07:15:41 -0700

>18.1.  Reserved Transport Parameters
>
>  Transport parameters with an identifier of the form "31 * N + 27" for
  integer values of N are reserved to exercise the requirement that
  unknown transport parameters be ignored.  These transport parameters
  have no semantics, and may carry arbitrary values.

Which hat did that come out of? It would be helpful to the reader to
explain the rational.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/4294

---

From: Marten Seemann <[email-masked]>
Date: Wed, 28 Oct 2020 07:37:43 -0700

That would be me. I made them up.
No hidden message here, sorry to disappoint!

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/4294#issuecomment-717976496

---

From: Mike Bishop <[email-masked]>
Date: Wed, 28 Oct 2020 08:50:54 -0700

Multiples of 31 ensures that they don't have a consistent bit signature but instead cycle through all of them; the 27 offset jumps over the region where we're defining things used in the core spec.

But the point is actually that the reader not need to understand the rationale, because the recipient should simply ignore unknown values like they're defined to.  Only the sender needs to be able to generate these, and this formula is a simple way to generate a value.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/4294#issuecomment-718026642