JPRIT / Event-1.21 / Tutorial.pdf-errata.txt 
Date: Wed, 23 Sep 2009 14:41:50 +0200 (CEST)
From: "Kiss Gabor (Bitman)" <kissg@ssg.ki.iif.hu>

In section 4.3 page 31 (33 according to PDF reader)
        warn "Event after ", time-startup, " seconds.\n";
should be changed to
        warn "Event after ", time-$startup, " seconds.\n";