El Thursday 08 May 2008 13:52:01 Robert Sparks escribió:
> No. If any are ever defined in the future they are guaranteed to be
> one letter.
>
> It's very unlikely that any new compact forms will ever be defined
> though- the argument is that if you need that kind of optimization,
> SIGCOMP does a better job.
>
> Here's what 4485 (sip-guidelines) has to say:
>
> Extensions that define new header fields that are anticipated to be
> heavily used MAY define a compact form if those header fields are
> more than six characters. "Heavily used" means that the percentage
> of all emitted messages that contain that header field is over
> thirty
> percent. Usage of compact forms in these cases is only a MAY
> because
> there are better approaches for reducing message overhead [20].
> Compact header fields MUST be a single character. When all 26
> characters are exhausted, new compact forms will no longer be
> defined. Header field names are defined by the "token" production
> in
> RFC 3261, Section 25.1, and thus include the upper and lowercase
> letters, the digits 0 through 9, the HYPHEN-MINUS (-), FULL STOP
> (.),
> EXCLAMATION MARK (!), PERCENT SIGN (%), ASTERISK (*), LOW LINE (_),
> PLUS SIGN (+), GRAVE ACCENT (`), APOSTROPHE ('), and TILDE (~).
> They
> SHOULD be descriptive but reasonably brief. Although header field
> names are case insensitive, a single common capitalization SHOULD be
> used throughout the document. It is RECOMMENDED that each English
> word present in the header field name have its first letter
> capitalized. For example, "ThisIsANewHeader".
Thanks a lot for so good explanation :)
--
Iñaki Baz Castillo
[EMAIL PROTECTED]
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