The capability declaration in Session Description Protocol (SDP) deals with certain attributes that enable it to provide a minimal and backwards compatible capability declaration mechanism because a session between conferencing parties needs to be established with a minimum set of common capabilities. Such a capability declaration can be used as an input to a subsequent session negotiation, which is done by means outside the scope of Request for Comments (RFC) 3407. This provides a simple and limited solution to the general capability negotiation problem being addressed by the SDP defined in RFC 3407.