4.3BSD-Tahoe/usr/lib/learn/eqn/L0.1a

#once #create message
.EQ
delim $$
.EN
.pl 1
.ll 55
This script is designed to teach you the "eqn" language
for typing mathematics. 
There are two versions of the program. "eqn" is for
use on the phototypesetter; "neqn" is for use on a
terminal like a DASI or GSI, or a Model 37 teletype.
The lessons are mostly written under the assumption
that you will be using neqn on a DASI or GSI or teletype;
a few things that are specific to eqn on the typesetter are
left to the end.

The terminal MUST be a DASI or GSI or teletype,
or you will get some rather startling results
from this script.

To verify that everything is working, this message
should come out with subscripts, superscripts, Greek
letters and so on.  If it doesn't, we're in
trouble.
.sp
Summation sign: $ sum $
.sp
Letter pi: $ pi $
.sp
Subscript and superscript: $ x sub i ~=~ y sup j $
.sp
If this looks ok, type yes.  Otherwise, type no.
.pl 1
#
#once neqn message | nroff -T$term
#copyin
#user
#uncopyin
#match yes
#fail
Do you have the right kind of terminal?
If you are using a DASI or GSI, make
sure the switch labeled "PLOT" inside the cover
is set to ON.
If these fail, call for help;
otherwise type yes the next time.
#log
#next
1.1a