[SIPForum-discussion] help:Header Field Format?

雨 陈 chen.yu26 at yahoo.com.cn
Wed Dec 19 13:54:46 UTC 2007

Hi, all
  Now , I meet a big problem in the SIP message parsing―the structure of header field:
  1.  field-name :  field-value
  on either side of the colon(":"), the arbitrary amount of whitespace is unlimited in theory. So what does the “whitespace” mean? a SP or HTAB?
  2. a folding field-value
     If the SIP header field values be folded onto multiple lines. 
  For instance,

   Subject: This is a test    =>     Subject: This

                                        is a test


So on the two lines, which kind of character will follow the word “This" and "test"as an end of each line?

Is there still a CRLF? before interpreting the field value of “Subject”, should I use a single SP instead of  all the special spaces between “This” and “is”?


Moreover, is there any possible that these following fields to be split into a multiple line representation? 

          Call-ID, CSeq, From, Context-Type
  Merry Christmas!

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