# [tex-eplain] eplain and Context

Dorai Sitaram dorai at ccs.neu.edu
Fri Apr 30 14:45:55 CEST 2004

>
> On Friday 30 April 2004 12:07 am, Stepan Kasal wrote:
> > Hello,
> >
> > On Thu, Apr 29, 2004 at 10:28:23PM -1000, John Culleton
> wrote:
> > > I have found that I can use eplain for some functions
> > > in a Context run if I comment out the line
> > > \def^^L{\par}%
> > >
> > > I have no idea, however what this line does. Can
> > > someone explain it to me?
> >
> > The character ctrl-L is form-feed, it's sometimes used
> > this way in text files.  This definition makes this
> > character equivalent to enf od paragraph.
> >
> > Stepan Kasal
>
> Yes, that is what I thought. But why ^^? Wouldn't a single ^
> do?

TeXbook, p. 45.  TeX uses the trigraph ^^<char> to represent a character
that whose ascii value is plus or minus 64 from <char>'s.   Thus the
three character-sequence ^^L is equivalent to the single character
(which you would get by typing ctrl-V ctrl-L in insert-mode in vi).

The ^ in ^^L can be any character whose current catcode is 7
(superscript).

> What happens is that if this line is left in place the
> following \def statement fails. This only happens in
> Context.
>
> In any case I always edit out all the ^L characters in Vim
> before processing, so it is not essential to me.