Aquí dejo el guión (script) con el que he resuelto el problema.

Código SQL [-]
ALTER TABLE PVP DROP CONSTRAINT PK_PVP_CODIGO;

ALTER TABLE PVP
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE PVP ADD CONSTRAINT PK_PVP_CODIGO PRIMARY KEY(CODIGO);


ALTER TABLE abonos
ALTER CODPRODUC TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE controlpesos
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE depositos
ALTER CODPRODUC TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE hdepositos
ALTER CODPRODUC TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE lineascompras
ALTER CODPRODUC TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE lineaspedidos
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;


ALTER TABLE lineasventas
ALTER CODPRODUC TYPE VARCHAR(12) CHARACTER SET ISO8859_1;


ALTER TABLE movalmacenes
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;


ALTER TABLE pvpsp
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE regulariza
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE tarifas
ALTER CODIGO TYPE VARCHAR(12) CHARACTER SET ISO8859_1;

ALTER TABLE tmplineasventas
ALTER CODPRODUC TYPE VARCHAR(12) CHARACTER SET ISO8859_1;



DROP TABLE FAMILIAS;


SET SQL DIALECT 3;



/******************************************************************************/
/*                                   Tables                                   */
/******************************************************************************/



CREATE TABLE FAMILIAS (
    CODIGO   VARCHAR(2) NOT NULL,
    FAMILIA  VARCHAR(35) NOT NULL
);




/******************************************************************************/
/*                                Primary Keys                                */
/******************************************************************************/

ALTER TABLE FAMILIAS ADD CONSTRAINT PK_FAMILIA_CODIGO PRIMARY KEY (CODIGO);


/******************************************************************************/
/*                                  Indices                                   */
/******************************************************************************/

CREATE UNIQUE INDEX ID_FAMILIA ON FAMILIAS (FAMILIA);


/******************************************************************************/
/*                                 Privileges                                 */
/******************************************************************************/

INSERT INTO FAMILIAS (CODIGO, FAMILIA)
              VALUES ('01', 'QUIMICOS');
INSERT INTO FAMILIAS (CODIGO, FAMILIA)
              VALUES ('02', 'CELULOSAS');
INSERT INTO FAMILIAS (CODIGO, FAMILIA)
              VALUES ('03', 'UTILES DE LIMPIEZA Y CARROS');
INSERT INTO FAMILIAS (CODIGO, FAMILIA)
              VALUES ('04', 'PLASTICOS Y BOLSAS');
INSERT INTO FAMILIAS (CODIGO, FAMILIA)
              VALUES ('05', 'DISPENSADORES');


COMMIT WORK;

Un Saludo.