+ *
+ * The routines sbappend() or sbappendrecord() are normally called to
+ * append new mbufs to a socket buffer, after checking that adequate
+ * space is available, comparing the function sbspace() with the amount
+ * of data to be added. sbappendrecord() differs from sbappend() in
+ * that data supplied is treated as the beginning of a new record.
+ * To place a sender's address, optional access rights, and data in a
+ * socket receive buffer, sbappendaddr() should be used. To place
+ * access rights and data in a socket receive buffer, sbappendrights()
+ * should be used. In either case, the new data begins a new record.
+ * Note that unlike sbappend() and sbappendrecord(), these routines check
+ * for the caller that there will be enough space to store the data.
+ * Each fails if there is not enough space, or if it cannot find mbufs
+ * to store additional information in.
+ *
+ * Reliable protocols may use the socket send buffer to hold data
+ * awaiting acknowledgement. Data is normally copied from a socket
+ * send buffer in a protocol with m_copy for output to a peer,
+ * and then removing the data from the socket buffer with sbdrop()
+ * or sbdroprecord() when the data is acknowledged by the peer.