{
{   The purpose  of  this  request is to scan the parameter list for a command
{ under control of a Parameter Descriptor Table.  This  request  may  only  be
{ invoked once an environment for the parameter list has been established.  An
{ environment is established automatically for a command processor,  but  must
{ be  explicitly  created (via clp$push_parameters) for a program other than a
{ command processor, or for a command  processor  which  wants  to  have  some
{ string interpreted as a parameter list.
{
{       CLP$SCAN_PARAMETER_LIST (PARAMETER_LIST, PDT, STATUS)
{
{ PARAMETER_LIST:  (input)  This  parameter specifies the parameter list to be
{       scanned.   Normally,  this  is  the  paramter  passed  to  a   command
{       processor.
{
{ PDT: (input) This parameter specifies the Parameter Descriptor Table for the
{       parameter list.
{
{ STATUS: (output) This parameter specifies the request status.
{
