--- /dev/null
+.TH rbldns-data 8
+
+.SH NAME
+rbldns-data \- data tool for rbldns
+
+.SH DESCRIPTION
+.B rbldns-data
+reads an IP address list
+from a file named
+.I data
+in the current directory.
+It creates
+.I data.cdb
+in a binary format designed for
+fast access by
+.BR rbldns (8).
+It may also create some other files
+with names beginning with
+.IR data .
+
+.B rbldns-data
+updates
+.I data.cdb
+atomically,
+so you can use it safely while
+.BR rbldns (8)
+is running.
+If anything goes wrong with the creation of
+.IR data.cdb ,
+.B rbldns-data
+stops and leaves the old
+.I data.cdb
+in place.
+
+.SH Data format
+
+.I ip
+
+The IP address
+.I ip
+is on the list.
+
+.I ip\fR/\fIn
+
+All IP addresses that share the first
+.I n
+bits
+of the IP address
+.I ip
+are on the list.
+For example,
+.I 1.2.3.0/24
+means all
+.I 1.2.3.*
+addresses.
+.I n
+must be at least 8,
+and all bits past the
+.IR n th
+in
+.I ip
+must be 0.
+
+.RI : a\fR:\fItxt\fR
+
+DNS queries for addresses on the list
+will receive an A record of
+.I a
+and a TXT record of
+.IR txt .
+Typically
+.I a
+is
+.I 127.0.0.2
+and
+.I txt
+is a pointer to a web page about the list.
+
+If
+.I txt
+ends with
+.IR $ ,
+.BR rbldns (8)
+replaces the
+.I $
+with the IP address.
+
+.RI # comment
+
+Comment line. The line is ignored.
+
+.SH SEE ALSO
+rbldns(8)
+
+http://cr.yp.to/djbdns.html