I have some issue with negative times in gnuplot.
Basically, I would like to write a negative time, e.g. as -00:01:00, but gnuplot is not interpreting it as -60 seconds, but as +60 seconds. I can somehow understand why: because -00 hours is equal to +00 hours and then01 minutes are counted positive.
myTimeFmt = "%tH:%tM:%tS"
print strptime(myTimeFmt,"-00:01:00")
print strptime(myTimeFmt,"+00:01:00")
will both result in +60 seconds, which is not what I would expect.
More details and an attempt of a workaround, see https://stackoverflow.com/q/60995400/7295599
Yes, a bug. Fixed now.