+.Dl $ apropos \-s 3 Va=optind \-a Va=optarg
+.Pp
+Do exactly the same as calling
+.Xr whatis 1
+with the argument
+.Qq ssh :
+.Pp
+.Dl $ apropos \-\- \-i 'Nm~[[:<:]]ssh[[:>:]]'
+.Pp
+The following two invocations are equivalent:
+.Pp
+.D1 Li $ apropos -S Ar arch Li -s Ar section expression
+.Bd -ragged -offset indent
+.Li $ apropos \e( Ar expression Li \e)
+.Li -a arch~^( Ns Ar arch Ns Li |any)$
+.Li -a sec~^ Ns Ar section Ns Li $
+.Ed