Firebird 6 introduces the CALL statement as an alternative to call executable stored procedures and excluding/limiting "out" parameters, and support for explicitly identifying the procedure or function parameter by name (also in EXECUTE PROCEDURE and selects).

• https://github.com/FirebirdSQL/firebird/blob/master/doc/sql.extensions/README.call.md
• https://github.com/FirebirdSQL/firebird/blob/master/doc/sql.extensions/README.named_arguments.md