[Sip-implementors] why do u need a parameter sub-field for media -range in the accept field?

[Prakash GS]

hi all         i hav 2 doubts  related to accept and accept-encoding.   (a)  The sip grammar defines the accept field as :-     Accept         = "Accept" ":"                         #( media-range [ accept-params ] )        media-range    = ( "*/*"                         | ( type "/" "*" )                         | ( type "/" subtype )                         ) *( ";" parameter )        accept-params  = ";" "q" "=" qvalue *( accept-extension )        accept-extension = ";" token [ "=" ( token | quoted-string ) ]   can someone tell me what ecaxtly is the use of the parameter sub-field in the media-range field .     (b)  according to an example in the http rfc 2616 ,the accept-encoding field may be left blank .Does this serve any purpose?          (examples from the rfc)                    Accept-Encoding = "Accept-Encoding" ":"                 1#( codings [ ";" "q" "=" qvalue ] ) codings = ( content-coding | "*" ) Examples of its use are: Accept-Encoding: compress, gzip Accept-Encoding: Accept-Encoding: * Accept-Encoding: compress;q=0.5, gzip;q=1.0 Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0     thanks in advance to whoever replies Regards Prakash Gs