https://github.com/michal-h21/lua4ht/blob/math/l4patchlatin1.lua
Cool, though it seems to me something simpler should be possible -- to
write a declaration for luatex at the beginning of the file that "this
file is in encoding xxx". (Of course that won't help when it contains
both Latin1 and Latin2, but that's a different issue.)
> Another idea is to move that chunk of input to a separate file, which
> only gets read when that option is in effect.
that might be perhaps the best solution?
Anything that works is fine with me, of course. I thought ^^ would be
the least invasive thing to try.
K