patch fix it -- but this patch doesn't contains tests or docs fixes. I
 will send it later.

 Fixed outputs:

select  to_char(x, '9999.999')  as x,
        to_char(x, 'S9999.999') as s,
        to_char(x, 'SG9999.999') as sg,
        to_char(x, 'MI9999.999') as mi,
        to_char(x, 'PL9999.999') as pl,
        to_char(x, 'PLMI9999.999') as plmi,
        to_char(x, '9999.999SG') as sg2,
        to_char(x, '9999.999PL') as pl2,
        to_char(x, '9999.999MI') as mi2 from num;

Karel Zak