Subject: Re: Ethernet PW question

From: Danny McPherson <[email-masked]>
Date: Wed, 17 Sep 2003 16:37:02 -0600

On Wednesday, September 17, 2003, at 04:21 PM, [email-masked] 
wrote:

> Eric/Shahram,
>
> 'may' and 'must' don't have the same strength in Engish IMO.  'May' 
> implies
> something as being 'at discretion' (ie optional), whereas 'must' 
> implies it
> is mandatory.

Folks, this could be a SHOULD NOT or more likely a MUST NOT, but
probably not a "MAY not" :-)

See RFC 2119 for further details on IETF speak, which is what matters
here:

1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
    definition is an absolute requirement of the specification.

2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the
    definition is an absolute prohibition of the specification.

3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
    may exist valid reasons in particular circumstances to ignore a
    particular item, but the full implications must be understood and
    carefully weighed before choosing a different course.

4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that
    there may exist valid reasons in particular circumstances when the
    particular behavior is acceptable or even useful, but the full
    implications should be understood and the case carefully weighed
    before implementing any behavior described with this label.

5. MAY   This word, or the adjective "OPTIONAL", mean that an item is
    truly optional.  One vendor may choose to include the item because a
    particular marketplace requires it or because the vendor feels that
    it enhances the product while another vendor may omit the same item.
    An implementation which does not include a particular option MUST be
    prepared to interoperate with another implementation which does
    include the option, though perhaps with reduced functionality. In the
    same vein an implementation which does include a particular option
    MUST be prepared to interoperate with another implementation which
    does not include the option (except, of course, for the feature the
    option provides.)

6. Guidance in the use of these Imperatives

    Imperatives of the type defined in this memo must be used with care
    and sparingly.  In particular, they MUST only be used where it is
    actually required for interoperation or to limit behavior which has
    potential for causing harm (e.g., limiting retransmisssions)  For
    example, they must not be used to try to impose a particular method
    on implementors where the method is not required for
    interoperability.

---

From: Loa Andersson <[email-masked]>
Date: Thu, 18 Sep 2003 00:35:27 +0200

All,

a hint is to refer to rfc 2119 and use "MUST NOT" as
defined, especially since "MAY NOT" is not defined in rfc 2119.
At least if we think that the intended meaning is close

/Loa

[email-masked] wrote:

> Eric/Shahram,
> 
> 'may' and 'must' don't have the same strength in Engish IMO.  'May' implies
> something as being 'at discretion' (ie optional), whereas 'must' implies it
> is mandatory.
> 
> regards, Neil
> 
> 
>>-----Original Message-----
>>From: Eric Rosen [mailto:[email-masked]]
>>Sent: 17 September 2003 14:31
>>To: Shahram Davari
>>Cc: [email-masked]'
>>Subject: Re: [PWE3] Ethernet PW question 
>>
>>
>>
>>
>>>>it may not rewrite or remove any tags which are already present."
>>
>>Shahram> Shouldn't  the last  sentence be:  however it  MUST 
>>not  rewrite or
>>Shahram> remove any tags which are already present. 
>>
>>I think  that "may not"  and "must not"  are synonymous in  
>>English, however
>>"MUST NOT" would probably the the most easily understood way 
>>of saying it. 
>>
>>
>>_______________________________________________
>>pwe3 mailing list
>>[email-masked]
>>https://www1.ietf.org/mailman/listinfo/pwe3
>>
> 
> 
> _______________________________________________
> pwe3 mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/pwe3
> 
> 

-- 
Loa Andersson

Mobile          +46 739 81 21 64
Email           [email-masked]

---

From: Eric Rosen <[email-masked]>
Date: Thu, 18 Sep 2003 10:57:03 -0400

Neil> 'may' and 'must' don't have the same strength in Engish IMO

But  "may  not"  and "must  not"  do.   "May  not"  is frequently  used  for
explicitly withholding permission to do something.

However, the  draft should  say "MUST NOT"  for clarity and  for conformance
with RFC 2119.