OpenBSD-4.6/usr.bin/learn/lib/eqn/L4.1d

#once #create message
.ND
.LP
You can put fractions over fractions with multiple "over"'s
just as you can do multiple subscripts and superscripts,
although fractions within fractions are much
less common (probably because they are harder for
people to read).
Anyway, if you want, for example, something like
.EQ
a over b over c
.EN
you just type
  .EQ
  a over b over c
  .EN

As a drill, change "Example" so it produces an equation
that looks like the following one, then type "ready".
.pl 1
#once #create Ref
.LP
.EQ
x over x+x over x+x+x
.EN
.pl 1
#once #create Example
.LP
.EQ
right here
.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
5.1a