{
{   The purpose of this request is to establish access to a specific
{ channelnet service access point.  Channelnet datagrams may be sent and
{ received over the opened service access point.
{
{       NLP$CN_OPEN_SAP (SAP, EVENT_PROCESSOR, MAXIMUM_DATA_LENGTH, STATUS)
{
{ SAP: (input) This parameter specifies the service access point which is to
{       be opened.
{
{ EVENT_PROCESSOR: (input) This parameter specifies a procedure to be called
{       whenever a datagram arrives which is destined for the service access
{       point which is to be opened.  This procedure will always be called in
{       the NAM/VE system task.  If this is not an appropriate task for
{       processing the received datagram, then it is the responsibility of the
{       procedure to switch processing to an appropriate task.
{
{ MAXIMUM_DATA_LENGTH: (output) This parameter specifies the maximum length of
{       the data which may be sent over the opened service access point in a
{       single datagram.
{
{ STATUS: (output) This parameter specifies the request status.
{       CONDITIONS: nae$sap_already_open
{       IDENTIFIER: 'NA'
{
