- * Maximum transport-layer message size (MMS_S) as per RFC 1122, 3.3.3
- * Socket must be connected.
+ * Get the maximum transport-layer message size (MMS_S).
+ *
+ * \param sockfd The socket file descriptor.
+ *
+ * The socket must be connected. See RFC 1122, 3.3.3. If the protocol familiy
+ * could not be determined, \p AF_INET is assumed.
+ *
+ * \return The maximum message size of the address family type.