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+#once #create message
+.ND
+.EQ
+delim $$
+.EN
+.LP
+You will get lots of practice
+using braces as we go along.
+One thing to keep in mind is that
+braces can appear ______within braces.
+(Remember that I said that anywhere you
+could use an "x" you could put something in
+braces instead.  So to get this:
+.EQ
+e sup {x sup {pi +1} + y sup {pi +1}}
+.EN
+you can type
+
+  e sup {x sup {pi +1} + y sup {pi +1}}
+
+The big superscript (the one on the "e") has
+a pair of braces that take in everything.
+Then the "x" and the "y" each have braces
+to delimit their superscripts.
+Of course the braces have to go in the right
+places, or you won't get the output you
+want.
+
+To verify that you are still following this
+lesson, modify "Example" so it looks like
+this, then type "ready".
+.pl 1
+#once #create Ref
+.LP
+.EQ
+e sup { - {x sup {pi +1} + y sup {pi +1}} over 2}
+.EN
+.pl 1
+#once #create Example
+.LP
+.EQ
+e sup {x sup {pi +1} + y sup {pi +1}}
+.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
+#fail
+Don't forget that you need braces for the overall superscript,
+and also for the "over" part.
+#log
+#next
+5.1e 10
+5.2d 5