{
{   The purpose of this request is to prepare a form for use by the program.
{ If the form_name is equal to OSC$NULL_NAME, then the form_identifier
{ specifies a dynamically created form.  Otherwise, Screen Formatting locates
{ the desired form by first searching the list of dynamically created forms
{ and then the forms specified by the command library list.  The
{ set_command_list specifies the command library list.  Fdp$open_form does not
{ display the form on the screen.  A form must be opened using fdp$open_form
{ before the form can be used by any other request.  The form_identifier
{ returned by this request identifies the instance of open for a form.  The
{ same form may have a number of open instances.  For each instance Screen
{ Formatting maintains the working environment of the form.  The working
{ environment includes the current value of variables and their display
{ attributes.
{
{       FDP$OPEN_FORM (FORM_NAME, FORM_IDENTIFIER, STATUS)
{
{ FORM_NAME: (input)  This parameter specifies the name of the form to open.
{       If the form name is equal to spaces, then Screen Formatting assumes
{       the form_identifier specifies the required dynamically created form.
{
{ FORM_IDENTIFIER:  (input/output) This parameter specifies the
{       form_identifier for other Screen Formatting requests to use when
{       referencing the form.
{
{ STATUS: (output) This parameter specifies the name of the variable to set
{       to indicate the status of the request.
{
{       condition identifiers: fde$bad_data_value
{                              fde$form_already_open
{                              fde$form_not_ended
{                              fde$form_requires_conversion
{                              fde$invalid_form_identifier
{                              fde$invalid_form_name
{                              fde$no_space_available
{                              fde$system_errors
{                              fde$terminal_not_identified
{                              fde$unknown_form_name
{
