(orig post hasn't come through yet otherwise I'd reply to it) In the ultimate internet faux pas I searched *after* I posted. The solution was staring me in the face, in a thread from this month: "Subtraction and NaN values".
Good grief. I apologize for adding noise. Ryan _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
