-.P
-The DNS lookups are usually the bottleneck for this mode, but we can
-perform them in parallel. Simply pass the number of threads to the GHC
-runtime on the command line; for example, the following will perform
-25 lookups in parallel:
-.P
+.SH OPTIONS
+
+.IP \fB\-\-barriers\fR,\ \fB\-b\fR
+(regexed mode only)
+
+Place barriers in front/back of the regex to prevent, for
+example, '127.0.0.1' from matching '127.0.0.100'. The downside is that
+the resulting regexp will match something that is not an IP address.
+This can interfere with things like \fIgrep -o\fR.
+
+Without \fB\-\-barriers\fR, you can match things you shouldn't:
+