> SHOW TABLE tb_iva
> COD_IVA VARCHAR(5) Not Null
> ALIQ_IVA (D_PERC) NUMERIC(9, 3)
> I_E VARCHAR(1) Not Null
> DETR_NE SMALLINT Not Null
> DES_IVA VARCHAR(20) Not Null
> CONSTRAINT INTEG_42:
> Primary key (COD_IVA)
>

I suppose D_PERC is a domain.

I think it isn't a solution, but can you try add another field numeric
(9,3), without using the domain D_PERC to check if go down in the 2
fields?

Which will be the result?

0.208 and 0.208
0.416 and 0.416
0.208 and 0

????????