{
{   The purpose of this request is to compute the time increment between an old
{ date and time and a new date and time.
{
{       PMP$COMPUTE_DATE_TIME_INCREMENT (OLD, NEW, INCREMENT, STATUS)
{
{ OLD: (input)  This parameter specifies the first date and time.
{
{ NEW: (input)  This parameter specifies the second date and time.  If OLD is
{       earlier in time than NEW, then INCREMENT will be positive.
{
{ INCREMENT: (output)  This parameter specifies the resulting date and time
{       increment, either positive or negative.
{
{ STATUS: (output) This parameter specifies the request status.
{       CONDITIONS: pme$compute_overflow
{                   pme$invalid_year
{
