Moving to sip-implementors:

  
-----Original Message-----
>From: Tom-PT Taylor [mailto:[EMAIL PROTECTED]]
>Sent: Wednesday, January 31, 2001 12:22 PM
>To: laks hmi; [EMAIL PROTECTED]
>Subject: RE: [SIP] Regarding header in SIP-URL
>
>
>Not according to the ABNF.  Looking at it logically, no header defined so
far has the 
>nature of a keyword whose very presence conveys useful information.  Hence
it will be 
>present with empty value only to say exactly that.  hname "=" says that
there is nothing 
>there more clearly than just hname.

Thats not correct. The BNF for the URL does, indeed, allow hvalue to be
empty. Furthermore, the sip spec defines the header fields thusly:

message-header = field-name ":" [ field-value ] CRLF

Notice that field value CAN be empty. It so happens that there are headers
which can have empty values. In particular, Accept-Encoding, which
explicitly says:

Note: An empty Accept-Encoding header field is permissible, even though the
syntax in [H14.3] does not
provide for it. It is equivalent to Accept-Encoding: identity, i.e., only
the identity encoding, meaning no encoding,
is permissible.


-Jonathan R.

> -----Original Message----- 
> From: laks hmi [mailto:[EMAIL PROTECTED]] 
> Sent: Wednesday, January 31, 2001 3:45 AM 
> To: [EMAIL PROTECTED] 
> Subject: [SIP] Regarding header in SIP-URL 
> 
> 
> Hi All, 
> 
> In SIP-URL, header = hname "=" hvalue. 
> Here hvalue can be zero or more, so in the 
> case of zero characters "=" character is not needed 
> So can i put header = hname [ "=" hvalue]. 
> 
> 
> Regards 
> lakshmi 
> 
> 
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---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[EMAIL PROTECTED]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com
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