.ds . \fB.\fP
.tr~
.ds . \fB.\fR
.		S1 - smaller in text
.de S1
.nh
.ps -1
..
.		S2 - reverse S1
.de S2
.ps +1
.hy
..
.de WS
.sp \\$1
..
.		H1 - start new section
.de H1
.SH
..
.		H2 - after H1 title
.de H2
..
.		X1 - start of example
.de X1
.nf
.in +.3i
.sp 4p
.if t .tr -\(en
..
.		X2 - end of example
.de X2
.sp 4p
.tr --
.in -.3i
.fi
..
.de PG
.PP
..