4.3BSD-Tahoe/usr/lib/learn/eqn/L11.1b

#once #create message
.ND
.tr %$
.EQ
delim $$
.EN
.LP
The quoting mechanism can also be used to turn off the special meaning
of things like the dollar sign and braces.
Modify "Example" so it prints the following output, then
type "ready".
.pl 1
#
#once #create Ref
.EQ
delim $$
.EN
.LP
The cost of processing is proportional to
$characters over "$"$.
.pl 1
#once #create Example
.LP
The cost of processing is proportional to
.pl 1
#
#once neqn Ref | nroff >X1 &
#once neqn message Ref | nroff -T$term %s/tinyms -
#user
neqn Example | nroff >X2
#cmp X1 X2
#log
#next
11.1c 10