Suppose that we have a font with a fixed encoding and want to change mapping between input characters and font slots. How to configure luatex so that if we type
A we get
B, not changing the font? An example input file follows.
\font\tenrm=cmr10 \tenrm A \bye
In the output document we need to get
$ luatex test.tex
NOTE: only luatex solution is needed (not lualatex)