To compute the time-of-flight we first add an integer multiple of the frame length to event_time_offset (and subtract the equivalent from event_time_zero).
Should the parenthetical read, "or subtract the equivalent from event_time_zero"?
That is, the actual time of flight is $$t = N \Delta T + \Delta t - T_0 = \Delta t - (T_0 - N \Delta T)$$
https://github.com/scipp/scippneutron/blob/d2237f7abcb52a74e1e3bef0df462c21e95c887d/docs/api-reference/frame-unwrapping.ipynb#L80C113-L80C163
Should the parenthetical read, "or subtract the equivalent from
event_time_zero"? That is, the actual time of flight is $$t = N \Delta T + \Delta t - T_0 = \Delta t - (T_0 - N \Delta T)$$