{
{  dup$locate_next_symbol locates the next symbol table entry (if the
{  symbol table exists).
{
{  DUP$LOCATE_NEXT_SYMBOL (SYMBOL_ADDRESS, SYMBOL_ENTRY, STATUS)
{
{  SYMBOL_ADDRESS : (input)    is a pointer to the debug symbol table.
{
{  SYMBOL_ENTRY : (input,output)  is a pointer to the current symbol
{                              table entry on input, and is a pointer
{                              to the next symbol table entry on output.
{                              The value returned = NIL if there are no
{                              more entries.
{
{  STATUS : (output)           is the status of the request. Possible value(s):
{                                due$no_symbol_table_in_module
{
