Consider this blog post by Lucky. Here's the first image:



There's a blue line that separates the first segment from the second, and second from third, but the 3rd and 4th segments are happily "stitched" together.

1. What's the significance of the blue line separator?

2. Why is there a separator for the first 3 segments but not between 3 and 4?

Now, I notice there's a change of date between the separated segments, while 3 and 4 have the same date. However, I just booked an itinerary that looks like this:

8/12 - 8/12 - segment 1
8/12 - 8/13 - segment 2
8/13 - 8/14 - segment 3
8/14 - 8/14 - segment 4

If date were the criterium for separation, then my itinerary would have no separation between 1 and 2, while it would have between the segments thereafter. However, the result is the exact opposite: there's only a separator between 1 and 2, while 2-4 are stitched together.

In my case, there was a change of airport between 1 and 2, so maybe that triggered the separation. Still, I can't figure out the exact criteria for separation.