{
{   The purpose of this request is to get the current screen value for a form
{ variable.  You cannot get the value from a pushed form.
{
{       FDP$GET_SCREEN_VARIABLE (FORM_IDENTIFIER, NAME, OCCURRENCE,
{         SCREEN_VARIABLE, STATUS)
{
{ FORM_IDENTIFIER: (input)  This parameter specifies the form identifier for
{       the instance of the form.
{
{ NAME: (input)  This parameter specifies the name of the variable.
{
{ OCCURRENCE: (input)  This parameter specifies the occurrence of the variable
{       name.
{
{ VARIABLE: (output)  This parameter returns the screen value of the variable.
{
{ STATUS: (output) This parameter specifies the name of the variable
{       to set to indicate the status of the request.
{
{       condition identifiers: fde$bad_data_value
{                              fde$invalid_form_identifier
{                              fde$system_error
{                              fde$unknown_occurrence
{                              fde$unknown_variable_name
{
