/usr/share/doc/nam/examples/iecdemos/make_dropevents is in nam-examples 1.15-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | #!/bin/sh
#
# this script looks for drops in the trace (.tr) file, and
# creates tcl code that will trigger nam annotations corresponding to them
#
egrep "^d" $1 | \
awk 'BEGIN { n=1 } { print "$ns at " $2 " \"$ns trace-annotate \\\"packet drop " n " (t=" $2 ")" "\\\"\""; ++n }';
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