header might be the precise nature of a new parameter to be added to an existing or other header will depend upon the header it could however be in the form of a generic parameter or a uri parameter in the case that the parameter is to be included in the proposed p served user header as defined in the ieft draft http tools ietforg wg sipping draft vanelburg sipping served user 05 txt the header structure set out in fig6 is possible where equal hcolon semi name addr addr spec and generic param are defined in rfc3261 the following is an example of a p served user header field with the proposed new parameter the actual u201c values u201d allowed for the user role can take any appropriate form however a number of likely roles are originating user orig terminating user term diversion div and transferring trans as these are known roles which are useful to the as i e these values allow the services as to identify if the served user is the originating or terminating party to the call or if they are a diverting or transferring user the logic deployed by the services will then depend upon the user role in the session of course the range of allowed values should remain extensible so that new roles can be defined when specific cases are identified fig7 shows the updated sequence vis u00e0 vis fig5 where the user role parameter has been included in the p served user header the presence of the user role parameter for user b with value u2018 div u2019 allows as 2 to determine the correct actions to take it will be noted in particular that.