Hi,
Below is ABNF from 3261 for tag–param.
From = ( "From" / "f" ) HCOLON from-spec
from-spec = ( name-addr / addr-spec )
*( SEMI from-param )
from-param = tag-param / generic-param
tag-param = "tag" EQUAL token
To = ( "To" / "t" ) HCOLON ( name-addr
/ addr-spec ) *( SEMI to-param )
to-param = tag-param / generic-param
It allows multiple tag-params in to and from headers. As “*” is put for
allowing any number of repetitions of {from|to}-param, which can have multiple tag-param itself.
We should limit it, at the most one occurrence of it, using
Section 3.6 of RFC 2234 .
I would suggest something of following syntax :-
To = ( "To" / "t" ) HCOLON ( name-addr
/ addr-spec ) to-additional-param
to-additional-param = ( 0*1(SEMI tag-param)) / ( *(SEMI generic-param))
The same applies to ABNF in Replaces and Join Header drafts for
replaces-param and join-param.
Thx
Samir
