+Physical markup:
+.Bl -column "xLix" description -offset indent -compact
+.It Li \&Em Ta italic font or underline
+.It Li \&Sy Ta boldface font
+.It Li \&Li Ta typewriter font
+.El
+.Pp
+Text production:
+.Bl -column "xLix" description -offset indent -compact
+.It Li \&St Ta reference to a standards document
+.It Li \&At Ta At No version reference
+.It Li \&Bx Ta Bx No version reference
+.It Li \&Bsx Ta Bsx No version reference
+.It Li \&Nx Ta Nx No version reference
+.It Li \&Fx Ta Fx No version reference
+.It Li \&Ox Ta Ox No version reference
+.It Li \&Dx Ta Dx No version reference
+.El