{
{    The purpose of this request is to ensure that the previous save area is
{ valid according to hardware specification.  A previous save area (a2) of NIL
{ in the current save area is valid by software convention.
{
{       PMP$VALIDATE_PREVIOUS_SAVE_AREA (CURRENT_SAVE_AREA, STATUS)
{
{ CURRENT_SAVE_AREA: (input)  This parameter specifies the save area whose
{       predecessor is to be validated.
{
{ STATUS: (output) This parameter specifies the outcome of the request -
{       abnormal status indicates an invalid previous save area.
{       CONDITIONS:
{             pme$inconsistent_stack
{
