gantt-Project starts 100-07-01 failed

Question

For gantt, when use the year before 1000, it failed.

Answer 1

With last snapshot, you can have:

@startgantt
Project starts 72-06-01.
printscale quarterly
[Construction of the Colosseum in Rome] starts 72-06-01 and requires 2920 days.
@endgantt

I am not 100% sure about the actual starting date.

Hope this helps, however we are really curious to know what you are actually doing with PlantUML !