/*

** Built-in: DEFAULT_VALUE
** Example: Make sure a Global variable is defined by
** assigning some value to it with Default_Value
*/
BEGIN
/*
** Default the value of GLOBAL.Command_Indicator if it is
** NULL or does not exist.
*/
Default_Value('***','global.command_indicator');
/*
** If the global variable equals the string we defaulted
** it to above, then it must have not existed before
*/
IF :Global.Command_Indicator = '***' THEN
Message('You must call this screen from the Main Menu');
RAISE Form_Trigger_Failure;
END IF;
END;