{
{   This request changes information in a clt$parameter_description_table.
{
{       CLP$CHANGE_PDT (PARAMETER_DESCRIPTION_TABLE, CHANGES, STATUS)
{
{ PARAMETER_DESCRIPTION_TABLE: (input)  This parameter specifies the
{       clt$parameter_description_table to be changed.  Note that the table
{       must be writable and that GENERATE_PDT produces the declarations for a
{       PDT in a read-only section, so the output from GENERATE_PDT must be
{       edited to allow this request to operate.
{
{ CHANGES: (input)  This parameer specifies the changes to be made.  The NUMBER
{       field of each element determines which parameter to change and the KIND
{       field determines what aspect of the parameter description is to be
{       changed as follows.
{
{       CLC$PDTC_AVAILABILITY:  specifies a new AVAILABILITY level for the
{             parameter.
{
{       CLC$PDTC_SECURITY:  specifies a new SECURITY level for the parameter.
{
{       CLC$PDTC_TYPE:  specifies changes to the type of the parameter.  The
{             TYPE_CHANGES are passed to CLP$CHANGE_TYPE_SPECIFICATION.
{
{       CLC$PDTC_DEFAULT_VALUE:  specifies a new DEFAULT_VALUE for the
{             parameter.  The default value in the original PDT must be large
{             enough to accommodate the new one.
{
{       CLC$PDTC_NULL:  can be used as a place holder in the changes array.
{
{ STATUS: (output)  This parameter specifies the request status.
{
