[texhax] some problems about \prevgraf and \toks

[Pierre MacKay]

I suppose the suggestion given in Ian Collier's response might work, but
it is reinventing the wheel.  Look at the EDMAC package for something
that has already been done.  I don't claim that finding your way around
EDMAC is easy, but it is known and tested.  I have used it for several
texts with marginal per-page line numbers.

Pierre MacKay