{
{   This request opens a file for command processing and creates an input block
{ to be used by the SCL interpreter when accessing the file.
{
{   This request deals with the special "files" CLC$CURRENT_COMMAND_INPUT and
{ CLC$PROC_CALLER_COMMAND_INPUT by only opening the actual command file if
{ necessary and creating an input block "inherited" from the appropriate
{ current input block.
{
{       CLP$PUSH_INPUT (FILE, UTILITY_NAME, PROMPT_STRING, ENABLE_ECHOING,
{         READ_ONLY, INPUT_BLOCK_HANDLE, FILE_ID, OPENED_EXECUTABLE_FILE,
{         FILE_OPEN, STATUS)
{
{ FILE: (input)  This parameter specifies the name of the file to be used.
{
{ UTILITY_NAME: (input)  This parameter specifies the utility name to be
{       associated with the input block.  OSC$NULL_NAME should be used if the
{       processing of the file is not associated with a utility.
{
{ PROMPT_STRING: (input)  This parameter specifies the "seed" prompt string to
{       be used when prompting for command input from a terminal.
{
{ ENABLE_ECHOING: (input)  This parameter specifies whether commands processed
{       within the input block created by this request may be echoed.  Note
{       that specifying TRUE for this parameter does NOT guarantee that echoing
{       will occur, only that it is allowed as far as the caller of this
{       request is concerned.
{
{ READ_ONLY: (input)  This parameter specifies whether the input block is being
{       created only for reading data (TRUE) or for command processing (FALSE).
{
{ INPUT_BLOCK_HANDLE: (output)  This parameter specifies the input block
{       created by this request.
{
{ FILE_ID: (output)  This parameter specifies the file_identifier if the file
{       was opened.  It is meaningless if the FILE_OPEN parameter is returned
{       as FALSE.
{
{ OPENED_EXECUTABLE_FILE: (output)  This parameter specifies whether the file
{       was opened for EXECUTEable access.  It is needed when calling the
{       corresponding CLP$POP_INPUT request.  It is meaningless if the
{       FILE_OPEN parameter is returned as FALSE.
{
{ FILE_OPEN: (output)  This parameter specifies whether the file was opened by
{       this request (TRUE) or not (FALSE).
{
{ STATUS: (output)  This parameter specifies the request status.
{
