#once #create message
.ND
.tr %$
.EQ
delim $$
.EN
.LP
As you might expect from our previous discussions,
any part of a

  thing from thing to thing

construction can be as complicated as you wish.
The only limitation is that the individual "thing"'s
may well need braces around them to make it
clear to neqn which part goes with which.

For example, suppose you want
.EQ
sum from {pi = 0} to {pi = n}
.EN
Then you have to ensure that the $pi =0$ and
$pi =n$ parts are included in braces or
they will not work right.

Modify file "Example" so the output looks like
the example above, then type "ready".
.pl 1
#once #create Ref
.LP
.EQ
sum from {pi = 0} to {pi =n}
.EN
.pl 1
#once #create Example
.LP
.EQ
sum from pi = 0 to pi = n
.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
7.1c 10
7.2b 5