Firebird - Execute Statement com Parâmetros

/* https://firebirdsql.org/rlsnotesh/rnfb25-psql-exctstmnt.html */

EXECUTE block
   RETURNS (
      VAL_A INTEGER,
      VAL_B INTEGER,
      VAL_C INTEGER
   )
AS
BEGIN


   -- Formato 1
   -- Variaveis nomeadas ( X, Y e Z )
   EXECUTE statement
      ('Select CAST(:X AS INT), CAST(:Y AS INT), CAST(:Z AS INT) from RDB$DATABASE')
      (X := 1, Y:=2, Z:=3)
   INTO
      :VAL_A,
      :VAL_B,
      :VAL_C;

   suspend;



   -- Formato 2
   -- Variaveis sem nome   "?"
   EXECUTE statement
      ('Select CAST(? AS INT), CAST(? AS INT), CAST(? AS INT) from RDB$DATABASE')
      (1,2,3)
   INTO
      :VAL_A,
      :VAL_B,
      :VAL_C;

   suspend;



END