rfc 3966 BNF queries

Hi, two queries here on RFC 3966 BNF issues.

Firstly, I was wondering if the optional BNF square brackets
around 
"visual-separator" in RFC 3966 was correct.

i.e.
 phonedigit = DIGIT / [ visual-separator ]

There's a discrepancy here with extension BNF, since
phonedigit is
essentially optional when visual-separator is made optional,
meaning the 1*
prefix to phonedigit there doesn't enforce that anything
goes after 
";ext=".

see:
 extension = ";ext=" 1*phonedigit

Secondly, what is the reason behind the errata posted below,
concerning 
change in isdn-subaddress BNF?

Reported By: Henning Schulzrinne <hgscs.columbia.edu>
Date: Tue, 01 Mar 2005 09:34:06 -0500

UNVERIFIED
Section 3 says:

isdn-subaddress      = ";isub=" 1*uric

It should say:

isdn-subaddress      = ";isub=" 1*paramchar


Thanks

-- 
Sincerely,
Eugene Seah


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Eugene Seah wrote:
> Hi, two queries here on RFC 3966 BNF issues.
> 
> Firstly, I was wondering if the optional BNF square
brackets around 
> "visual-separator" in RFC 3966 was correct.
> 
> i.e.
> phonedigit = DIGIT / [ visual-separator ]
> 
> There's a discrepancy here with extension BNF, since
phonedigit is
> essentially optional when visual-separator is made
optional, meaning the 1*
> prefix to phonedigit there doesn't enforce that
anything goes after 
> ";ext=".
> 
> see:
> extension = ";ext=" 1*phonedigit

You are right - this is really messed up. And the same is
true of 
phonedigit-hex.

(Because of the way they are used this is only technically a
problem 
with 'extension'.)

I think a correct way of stating this would be:

    phonedigit           = [visual-separator] DIGIT
[visual-separator]
    phonedigit-hex       = [visual-separator] HEXDIG /
"*" / "#"
                           [visual-separator]


	Paul

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On 4/13/2007 6:00 PM, Paul Kyzivat wrote:
>
> Eugene Seah wrote:
>> Hi, two queries here on RFC 3966 BNF issues.
>>
>> Firstly, I was wondering if the optional BNF square
brackets around 
>> "visual-separator" in RFC 3966 was
correct.
>>
>> i.e.
>> phonedigit = DIGIT / [ visual-separator ]
>>
>> There's a discrepancy here with extension BNF,
since phonedigit is
>> essentially optional when visual-separator is made
optional, meaning 
>> the 1*
>> prefix to phonedigit there doesn't enforce that
anything goes after 
>> ";ext=".
>>
>> see:
>> extension = ";ext=" 1*phonedigit
>
> You are right - this is really messed up. And the same
is true of 
> phonedigit-hex.
>
> (Because of the way they are used this is only
technically a problem 
> with 'extension'.)
>
> I think a correct way of stating this would be:
>
>    phonedigit           = [visual-separator] DIGIT
[visual-separator]
>    phonedigit-hex       = [visual-separator] HEXDIG /
"*" / "#"
>                           [visual-separator]
>
Implying the following changes as well?

global-number-digits = "+" 1*phonedigit

local-number-digits  = 1*phonedigit-hex 

Also, any idea about part 2 of my post, namely the reason
for RFC ERRATA:
";isub=" 1*paramchar instead of ";isub="
1*uric?

Thanks.


-- 
Sincerely,
Eugene Seah


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I agree. I guess the next step would be filing an RFC
erratum.

On Apr 13, 2007, at 8:00 PM, Paul Kyzivat wrote:

>
>
> Eugene Seah wrote:
>> Hi, two queries here on RFC 3966 BNF issues.
>> Firstly, I was wondering if the optional BNF square
brackets  
>> around "visual-separator" in RFC 3966 was
correct.
>> i.e.
>> phonedigit = DIGIT / [ visual-separator ]
>> There's a discrepancy here with extension BNF,
since phonedigit is
>> essentially optional when visual-separator is made
optional,  
>> meaning the 1*
>> prefix to phonedigit there doesn't enforce that
anything goes  
>> after ";ext=".
>> see:
>> extension = ";ext=" 1*phonedigit
>
> You are right - this is really messed up. And the same
is true of  
> phonedigit-hex.
>
> (Because of the way they are used this is only
technically a  
> problem with 'extension'.)
>
> I think a correct way of stating this would be:
>
>    phonedigit           = [visual-separator] DIGIT
[visual-separator]
>    phonedigit-hex       = [visual-separator] HEXDIG /
"*" / "#"
>                           [visual-separator]
>
>
> 	Paul
>
> _______________________________________________
> Iptel mailing list
> Iptelietf.org
> https://
www1.ietf.org/mailman/listinfo/iptel


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Eugene Seah wrote:
> On 4/13/2007 6:00 PM, Paul Kyzivat wrote:
>>
>> Eugene Seah wrote:
>>> Hi, two queries here on RFC 3966 BNF issues.
>>>
>>> Firstly, I was wondering if the optional BNF
square brackets around 
>>> "visual-separator" in RFC 3966 was
correct.
>>>
>>> i.e.
>>> phonedigit = DIGIT / [ visual-separator ]
>>>
>>> There's a discrepancy here with extension BNF,
since phonedigit is
>>> essentially optional when visual-separator is
made optional, meaning 
>>> the 1*
>>> prefix to phonedigit there doesn't enforce that
anything goes after 
>>> ";ext=".
>>>
>>> see:
>>> extension = ";ext=" 1*phonedigit
>>
>> You are right - this is really messed up. And the
same is true of 
>> phonedigit-hex.
>>
>> (Because of the way they are used this is only
technically a problem 
>> with 'extension'.)
>>
>> I think a correct way of stating this would be:
>>
>>    phonedigit           = [visual-separator] DIGIT
[visual-separator]
>>    phonedigit-hex       = [visual-separator] HEXDIG
/ "*" / "#"
>>                           [visual-separator]
>>
> Implying the following changes as well?
> 
> global-number-digits = "+" 1*phonedigit
> 
> local-number-digits  = 1*phonedigit-hex

While the existing syntax would work with just the other
changes, these 
changes you suggest are simpler and would be clearer.

> Also, any idea about part 2 of my post, namely the
reason for RFC ERRATA:
> ";isub=" 1*paramchar instead of
";isub=" 1*uric?

Nope - not a clue.

	Paul

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Hi Eugene, folks,
    Richard Stastny pointed out to me that RFC 4715 covers
ISDN
subaddressing with the tel URI (and ISUP/SIP/ISUP
interworking).
  Look there for (most of) the gory details.

That's the good news.
(see also my next message)

all the best,
   Lawrence



On 13 Apr 2007, at 23:05, Eugene Seah wrote:
> Secondly, what is the reason behind the errata posted
below,  
> concerning change in isdn-subaddress BNF?
>
> Reported By: Henning Schulzrinne <hgscs.columbia.edu>
> Date: Tue, 01 Mar 2005 09:34:06 -0500
> UNVERIFIED
> Section 3 says:
> isdn-subaddress      = ";isub=" 1*uric
> It should say:
> isdn-subaddress      = ";isub=" 1*paramchar


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On 4/13/2007 8:43 PM, Henning Schulzrinne wrote:
> I agree. I guess the next step would be filing an RFC
erratum.
>
> On Apr 13, 2007, at 8:00 PM, Paul Kyzivat wrote:
>
>>
>>
>> Eugene Seah wrote:
>>> Hi, two queries here on RFC 3966 BNF issues.
>>> Firstly, I was wondering if the optional BNF
square brackets around 
>>> "visual-separator" in RFC 3966 was
correct.
>>> i.e.
>>> phonedigit = DIGIT / [ visual-separator ]
>>> There's a discrepancy here with extension BNF,
since phonedigit is
>>> essentially optional when visual-separator is
made optional, meaning 
>>> the 1*
>>> prefix to phonedigit there doesn't enforce that
anything goes after 
>>> ";ext=".
>>> see:
>>> extension = ";ext=" 1*phonedigit
>>
>> You are right - this is really messed up. And the
same is true of 
>> phonedigit-hex.
>>
>> (Because of the way they are used this is only
technically a problem 
>> with 'extension'.)
>>
>> I think a correct way of stating this would be:
>>
>>    phonedigit           = [visual-separator] DIGIT
[visual-separator]
>>    phonedigit-hex       = [visual-separator] HEXDIG
/ "*" / "#"
>>                           [visual-separator]
Thanks for your replies, these BNF changes to 'phonedigit'
and 
'phone-digit-hex' do change the permitted BNF for the 
'global-number-digits', 'local-number-digits' and
'extension' 
constructs, I just want to clarify that this change is
intentional.

  global-number-digits = "+" *phonedigit DIGIT
*phonedigit

  local-number-digits  =
      *phonedigit-hex (HEXDIG / "*" /
"#")*phonedigit-hex

e.g. previously, a uri such as "tel:+()()1" would
be allowed under the 
BNF, but with the change in 'phonedigit', visual-separators
must be 
neighbored by as least one DIGIT (or 
HEXDIG/"*"/"#" for local numbers).

Does that new limitation sound right or are there valid
examples of 
telephone numbers where visual-separators shouldn't need to
be 
neighbored by these symbols?

Thanks.


-- 
Sincerely,
Eugene Seah


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Iptelietf.org
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www1.ietf.org/mailman/listinfo/iptel

It strikes me that if this is to be judged as a
"bug" then we need to 
ascertain what the *intent* was and then come up with a
valid ABNF that 
realizes the intent. Otherwise we are simply devising
another extension.

I don't know what the intent was. I can only guess at what
seems 
"reasonable" to me.

	Paul

Eugene Seah wrote:
> On 4/13/2007 8:43 PM, Henning Schulzrinne wrote:
>> I agree. I guess the next step would be filing an
RFC erratum.
>>
>> On Apr 13, 2007, at 8:00 PM, Paul Kyzivat wrote:
>>
>>>
>>>
>>> Eugene Seah wrote:
>>>> Hi, two queries here on RFC 3966 BNF
issues.
>>>> Firstly, I was wondering if the optional
BNF square brackets around 
>>>> "visual-separator" in RFC 3966
was correct.
>>>> i.e.
>>>> phonedigit = DIGIT / [ visual-separator ]
>>>> There's a discrepancy here with extension
BNF, since phonedigit is
>>>> essentially optional when visual-separator
is made optional, meaning 
>>>> the 1*
>>>> prefix to phonedigit there doesn't enforce
that anything goes after 
>>>> ";ext=".
>>>> see:
>>>> extension = ";ext=" 1*phonedigit
>>>
>>> You are right - this is really messed up. And
the same is true of 
>>> phonedigit-hex.
>>>
>>> (Because of the way they are used this is only
technically a problem 
>>> with 'extension'.)
>>>
>>> I think a correct way of stating this would
be:
>>>
>>>    phonedigit           = [visual-separator]
DIGIT [visual-separator]
>>>    phonedigit-hex       = [visual-separator]
HEXDIG / "*" / "#"
>>>                           [visual-separator]
> Thanks for your replies, these BNF changes to
'phonedigit' and 
> 'phone-digit-hex' do change the permitted BNF for the 
> 'global-number-digits', 'local-number-digits' and
'extension' 
> constructs, I just want to clarify that this change is
intentional.
> 
>  global-number-digits = "+" *phonedigit DIGIT
*phonedigit
> 
>  local-number-digits  =
>      *phonedigit-hex (HEXDIG / "*" /
"#")*phonedigit-hex
> 
> e.g. previously, a uri such as "tel:+()()1"
would be allowed under the 
> BNF, but with the change in 'phonedigit',
visual-separators must be 
> neighbored by as least one DIGIT (or 
HEXDIG/"*"/"#" for local numbers).
> 
> Does that new limitation sound right or are there valid
examples of 
> telephone numbers where visual-separators shouldn't
need to be 
> neighbored by these symbols?
> 
> Thanks.
> 
> 

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I don't recall how and why this happened, but RFC 2806 (the 

predecessor) had

phonedigit            = DIGIT / visual-separator

This would have allowed multiple separators in sequence.

I also checked the draft history, and the original version
in

http://tools.ietf.org/html/draft-ietf-iptel-rfc2806bis-
00 and 01

has

honedigit            =  DIGIT [ visual-separator ]

which is close to what's being proposed. This changed to the
current  
format in -02.

The only change log entry is

Changes from ietf-00 to ietf-01

         o Editorial changes suggested by Francois Audet.


I also checked my mail folder and the IETF mailing archive
around the  
time 02 was issued, and there's no discussion on this
feature that I  
can find.

Personally, I don't see the need for multiple consecutive
separators.

Henning

On Apr 16, 2007, at 7:32 PM, Paul Kyzivat wrote:

> It strikes me that if this is to be judged as a
"bug" then we need  
> to ascertain what the *intent* was and then come up
with a valid  
> ABNF that realizes the intent. Otherwise we are simply
devising  
> another extension.
>
> I don't know what the intent was. I can only guess at
what seems  
> "reasonable" to me.
>
> 	Paul
>
> Eugene Seah wrote:
>> On 4/13/2007 8:43 PM, Henning Schulzrinne wrote:
>>> I agree. I guess the next step would be filing
an RFC erratum.
>>>
>>> On Apr 13, 2007, at 8:00 PM, Paul Kyzivat
wrote:
>>>
>>>>
>>>>
>>>> Eugene Seah wrote:
>>>>> Hi, two queries here on RFC 3966 BNF
issues.
>>>>> Firstly, I was wondering if the
optional BNF square brackets  
>>>>> around "visual-separator" in
RFC 3966 was correct.
>>>>> i.e.
>>>>> phonedigit = DIGIT / [ visual-separator
]
>>>>> There's a discrepancy here with
extension BNF, since phonedigit is
>>>>> essentially optional when
visual-separator is made optional,  
>>>>> meaning the 1*
>>>>> prefix to phonedigit there doesn't
enforce that anything goes  
>>>>> after ";ext=".
>>>>> see:
>>>>> extension = ";ext="
1*phonedigit
>>>>
>>>> You are right - this is really messed up.
And the same is true  
>>>> of phonedigit-hex.
>>>>
>>>> (Because of the way they are used this is
only technically a  
>>>> problem with 'extension'.)
>>>>
>>>> I think a correct way of stating this would
be:
>>>>
>>>>    phonedigit           =
[visual-separator] DIGIT [visual- 
>>>> separator]
>>>>    phonedigit-hex       =
[visual-separator] HEXDIG / "*" / "#"
>>>>                          
[visual-separator]
>> Thanks for your replies, these BNF changes to
'phonedigit' and  
>> 'phone-digit-hex' do change the permitted BNF for
the 'global- 
>> number-digits', 'local-number-digits' and
'extension' constructs,  
>> I just want to clarify that this change is
intentional.
>>  global-number-digits = "+" *phonedigit
DIGIT *phonedigit
>>  local-number-digits  =
>>      *phonedigit-hex (HEXDIG / "*" /
"#")*phonedigit-hex
>> e.g. previously, a uri such as
"tel:+()()1" would be allowed under  
>> the BNF, but with the change in 'phonedigit',
visual-separators  
>> must be neighbored by as least one DIGIT (or 
HEXDIG/"*"/"#" for  
>> local numbers).
>> Does that new limitation sound right or are there
valid examples  
>> of telephone numbers where visual-separators
shouldn't need to be  
>> neighbored by these symbols?
>> Thanks.
>
> _______________________________________________
> Iptel mailing list
> Iptelietf.org
> https://
www1.ietf.org/mailman/listinfo/iptel


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