[rrd-users] Struggling with rrdtool graph function.

[Randy]

I currently use rrd to store 5 minute snapshots of incoming and  
outgoing data which I can access via a CGI script using this function:

<RRD::GRAPH $NODE-test.png
   --start $START --end now
   DEF:in=$DB:in:AVERAGE
   DEF:out=$DB:out:AVERAGE
   VDEF:intot=in,TOTAL
   VDEF:outtot=out,TOTAL
   CDEF:grand=in,out,+
   VDEF:grandtot=grand,TOTAL
   CDEF:siset=in,0,*,1000000,+
   PRINT:siset:MAX:"%.lf %s"
   PRINT:intot:"%.lf %SBytes"
   PRINT:outtot:"%.lf %SBytes"
   PRINT:grandtot:"%.lf %SBytes">

However, this gives me the total data used for a specific time period  
based on a 24 hour day. What I really want is  the total data used  
during a specific time period and only during 8am to 10pm. Is there a  
way to do this using rrdgraph? I can't seem to wrap my head around it.