{
{    The purpose of this function is to verify the validity of a message
{ identifier.  This function is of interest since messages and their associated
{ identifiers have different lifetimes.  Some buffer manager interfaces return
{ invalid identifiers to indicate that the message being operated on has been
{ released.
{
{       NLP$BM_VALID_MESSAGE_ID (MESSAGE_ID)
{
{ MESSAGE_ID: (input)  This parameter specifies the message identifier whose
{       validity is to be verified.
{
