4.3BSD-Tahoe/usr/lib/learn/eqn/L9.1b

#once #create message
.ND
.tr %$
.EQ
delim $$
.EN
.LP
You sometimes have to make explicit what you
mean when you say "bar", by putting in braces
to enclose the parts that you want the bar
to be over. 
For example, what has to be done to make
the output
.EQ
{x sub i} bar
.EN
Find out (by putting braces in the right place
if necessary) in the file "Example", then
type "ready" after you have successfully modified it.
.pl 1
#once #create Ref
.EQ
delim $$
.EN
.LP
.EQ
{x sub i} bar
.EN
.pl 1
#once #create Example
.EQ
delim $$
.EN
.LP
.EQ
x sub i bar
.EN
.pl 1
#
#once neqn Ref | nroff >X1 &
#once neqn message Ref | nroff -T$term %s/tinyms -
#user
neqn Example | nroff >X2
#cmp X1 X2
#log
#next
10.1a 10
9.2b 5