In this illustration, we see a dotted line extending horizontally from left to right, representing the passage of time. Three dashed lines rise vertically up from the timeline in three places: one to the left, one in the middle, and one to the right. The first dashed line (from left to right) is labeled t0 - 1. The middle line is labeled t0. And the third line is labeled t0 + 1. A blue rectangle spans the distance between the middle and third lines, and this rectangle is labeled "Node i frame." Labels at the top of the figure indicate that the space between the first and middle lines "Will overlap with start of i's frame," and the space between the middle and third line "Will overlap with end of i's frame." A light blue rectangle above Node i frame begins just beyond the first line and ends just beyond the middle line. And a light blue rectangle below Node i frame begins just before the third line and extends beyond it.