{
{   The purpose of this procedure is to explicitly set the segment length.
{ Segment length is defined as the last byte in the segment that can be
{ referenced, references beyond segment length are treated the same as a
{ read beyond EOI.
{
{        MMP$SET_SEGMENT_LENGTH (PVA, VALIDATION_RING_NUMBER, SEGMENT_LENGTH,
{          STATUS)
{
{ PVA: (input) This parameter specifies the segment for which segment length
{        is being set.
{
{ VALIDATION_RING_NUMBER: (input) This parameter specifies the ring number
{        used for validation if it is greater than the caller ring number.
{
{ SEGMENT_LENGTH: (input) This parameter specifies the new segment length.
{
{ STATUS: (output) This parameter is where the request status is returned
{        to the caller.  The possible error codes are:
{              mme$caller_not_in_write_bracket
{              mme$invalid_pva
{              mme$no_write_access
{              mme$ref_to_unrecovered_file
{              mme$segment_number_not_in_use
{              mme$segment_number_too_big
{
