Subject: the terms "priority" and "precedence"

From: Michael Richardson <[email-masked]>
Date: Tue, 18 Jul 2017 13:54:02 +0200

We have many places in protocols where we want to express some ordering of
pieces of information.  We call these fields priority or precedence or
sometimes other things.  Give encode things as numbers.

DNS's MX record has a "preference", in which lower numbers are better.
BGP has a LOCAL_PREF, in which higher numbers are better.
RAs have PreferenceLevel, in which higher numbers are better.
ROLL has "rank", in which lower numbers mean closer to the root.
OSPF has such numbers, which I forget at the moment.

Is there any consistent usage where preference is a term used when
higher numbers are better and priority when lower numbers are better?
Does the RFC-editor have any suggestions?  Or is it really all random.

--
]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        | network architect  [
]     [email-masked]  http://www.sandelman.ca/        |   ruby on rails    [

--
Michael Richardson <[email-masked]>, Sandelman Software Works
 -= IPv6 IoT consulting =-

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From: Brian E Carpenter <[email-masked]>
Date: Wed, 19 Jul 2017 08:53:49 +1200

> pieces of information.  We call these fields priority or precedence or

Just a side note: in the design of diffserv we paid a lot of attention
to that choice of words. You might care to read section 4.2.1 of RFC2474,
which could be summarised as precedence != priority. I think there is
quite some subtlety in this area, and not so much randomness in the choices.

   Brian

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From: "tom p." <[email-masked]>
Date: Fri, 21 Jul 2017 11:10:44 +0100

Michael

I agree with Brian that priority and precedence are different.

For me, priority is something that can be ordered, a number, perhaps a
character or a string of characters, unbounded but where I cannot tell
whether higher or lower is better without being told.

Precedence is more binary, one or a group coming before another one or
group.  I note however that my dictionary also gives a definition of
precedence as a form of priority:-)

Tom Petch