OpenBSD-4.6/usr.bin/learn/lib/eqn/L5.2b

#once #create message
.ND
.EQ
delim $$
.EN
.LP
Try another example with braces, for practice.
Make the file "Example" produce output that looks
like this line, then type "ready".
(The character $rho$ is "rho".)
.pl 1
#once #create Ref
.LP
.EQ
alpha sub i sup {pi + rho + 1} ~=~ 1
.EN
.pl 1
#once #create Example
.LP
.EQ
replace me
.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
5.1c 10