Re: ispell language per buffer, not for all buffers

[Richard Stallman]

    Yes, I forgot ispell also allows "accept for this session". In this case,
    starting one ispell per buffer seems to be the only alternative or has
    ispell some command like --accept-these-words-in-this-session-only?.

If we want to be able to "accept for this document only", it would
require either an Ispell per buffer or a new Ispell feature that lets
one Ispell process record various environments.  The former is too
expensive, but I think the latter would be a good feature for Ispell.
I will suggest it to the maintainer now.