{
{   The purpose of this request is to close/delete a segment.  If the
{ caller is not within the read bracket of the segment being closed the
{ call is rejected.
{
{       MMP$CLOSE_SEGMENT (POINTER, VALIDATION_RING_NUMBER, STATUS)
{
{ POINTER: (input_output) This parameter specifies the segment
{       to be deleted.  This pointer will be set to NIL when the
{       request completes.
{
{ VALIDATION_RING_NUMBER: (input) This parameter specifies the ring of
{       execution for whom the segment is being closed.  The ring
{       number used for validation is the max of the caller ring number
{       and 'validation_ring_number'.
{
{ STATUS: (output) This parameter specifies the request status.
{       The possible error codes are:
{             dme$file_descriptor_not_deleted
{             mme$invalid_close_segment_req
{             mme$invalid_shared_taskid
{             mme$segment_number_not_in_use
{             mme$segment_number_too_big
{
