[Fontinst] kerns for digits

[Thanh Han The]

Dear list,

I use fontinst to create tex support for some vietnamese fonts. Recently
I got a bug report that the fonts contain undesired kern
pairs for digits. I did a quick test as following:

,--------
| \input fontinst.sty
| 
| \transformfont{pplr8r}{\reencodefont{8r}{\fromafm{pplr8a}}}
| \installfonts
| \installrawfont {pplr8r}{pplr8r,8r}{8r} {8r}{ppl}{m}{n}{}
| \installfont {pplr8t}{pplr8r,newlatin}{t1} {T1}{ppl}{m}{n}{}
| \endinstallfonts
| 
| \bye
`--------

and pplr8t indeed contains kerns for digits (for example 1 <-> 1)

I have been digging for a while in fontinst sources and
documentation to find out why the fonts coming with texlive
and tetex don't have this problem, but without success. Can
someone please give me a hint what I am missing?

Thanks,
Thanh