-The same RRD file and B<RRAs> are created with the following command, which explicitly
-creates all specialized function B<RRAs>.
-
-C<rrdtool create monitor.rrd --step 300
-DS:ifOutOctets:COUNTER:1800:0:4294967295
-RRA:AVERAGE:0.5:1:2016
-RRA:HWPREDICT:1440:0.1:0.0035:288:3
-RRA:SEASONAL:288:0.1:2
-RRA:DEVPREDICT:1440:5
-RRA:DEVSEASONAL:288:0.1:2
-RRA:FAILURES:288:7:9:5>
-
-Of course, explicit creation need not replicate implicit create, a number of arguments
-could be changed.
+The same RRD file and B<RRAs> are created with the following command,
+which explicitly creates all specialized function B<RRAs>.
+
+ rrdtool create monitor.rrd --step 300 \
+ DS:ifOutOctets:COUNTER:1800:0:4294967295 \
+ RRA:AVERAGE:0.5:1:2016 \
+ RRA:HWPREDICT:1440:0.1:0.0035:288:3 \
+ RRA:SEASONAL:288:0.1:2 \
+ RRA:DEVPREDICT:1440:5 \
+ RRA:DEVSEASONAL:288:0.1:2 \
+ RRA:FAILURES:288:7:9:5
+
+Of course, explicit creation need not replicate implicit create, a
+number of arguments could be changed.
+
+=head1 EXAMPLE 3
+
+ rrdtool create proxy.rrd --step 300 \
+ DS:Total:DERIVE:1800:0:U \
+ DS:Duration:DERIVE:1800:0:U \
+ DS:AvgReqDur:COMPUTE:Duration,Requests,0,EQ,1,Requests,IF,/ \
+ RRA:AVERAGE:0.5:1:2016
+
+This example is monitoring the average request duration during each 300 sec
+interval for requests processed by a web proxy during the interval.
+In this case, the proxy exposes two counters, the number of requests
+processed since boot and the total cumulative duration of all processed
+requests. Clearly these counters both have some rollover point, but using the
+DERIVE data source also handles the reset that occurs when the web proxy is
+stopped and restarted.
+
+In the B<RRD>, the first data source stores the requests per second rate
+during the interval. The second data source stores the total duration of all
+requests processed during the interval divided by 300. The COMPUTE data source
+divides each PDP of the AccumDuration by the corresponding PDP of
+TotalRequests and stores the average request duration. The remainder of the
+RPN expression handles the divide by zero case.