| sip_accept_s | Structure for Accept header field |
| sip_addr_s | Structure for From and To headers |
| sip_alert_info_s | Structure for Alert-Info header |
| sip_allow_s | Structure for Allow header field |
| sip_authentication_info_s | Structure for Authentication-Info header |
| sip_call_id_s | Structure for Call-ID (and In-Reply-To) header fields |
| sip_call_info_s | Structure for Call-Info header |
| sip_caller_prefs_s | Structure for Accept-Contact and Reject-Contact header fields |
| sip_contact_s | Structure for Contact header field |
| sip_content_length_s | Structure for Content-Length header |
| sip_content_type_s | Structure for Content-Type header |
| sip_cseq_s | Structure for CSeq header |
| sip_date_s | Structure for Date header |
| sip_error_info_s | Structure for Error-Info header |
| sip_event_s | Structure for Event header |
| sip_expires_s | Structure for Expires header |
| sip_max_forwards_s | Structure for Max-Forwards header |
| sip_min_expires_s | Structure for Min-Expires header |
| sip_min_se_s | Structure for Min-SE header |
| sip_p_asserted_identity_s | Structure for P-Asserted-Identity header |
| sip_p_preferred_identity_s | Structure for P-Preferred-Identity header |
| sip_pref | Possible values for SIP media tags |
| sip_privacy_s | Structure for Privacy header |
| sip_rack_s | Structure for RAck header |
| sip_reason_s | Structure for Reason header field |
| sip_refer_sub_s | Structure for Refer-Sub header |
| sip_refer_to_s | Structure for Refer-To header |
| sip_referred_by_s | Structure for Referred-By header |
| sip_remote_party_id_s | Structure for Remote-Party-ID header |
| sip_replaces_s | Structure for Replaces header |
| sip_reply_to_s | Structure for Reply-To header |
| sip_request_disposition_s | Structure for Request-Disposition header |
| sip_request_s | Structure for SIP request line |
| sip_retry_after_s | Structure for Retry-After header |
| sip_route_s | Structure for Route and Record-Route header fields |
| sip_rseq_s | Structure for RSeq header |
| sip_s | SIP message object |
| sip_security_agree_s | Structure for Security-Client, Security-Server, and Security-Verify headers |
| sip_session_expires_s | Structure for Session-Expires header |
| sip_status_s | Structure for SIP status line |
| sip_subscription_state_s | Structure for Subscription-State header |
| sip_suppress_body_if_match_s | Structure for Suppress-Body-If-Match header |
| sip_suppress_notify_if_match_s | Structure for Suppress-Notify-If-Match header |
| sip_timestamp_s | Structure for Timestamp header |
| sip_via_s | Structure for Via header field |
| sip_pref::sp_literal | Literal (tag="foo") |
| sip_pref::sp_range | Numeric value or range (tag="#=1"; tag="#<=3"; tag="#>=-2"; tag="#1:6") |
| sip_pref::sp_string | String (tag="<foo>") |
