This case tests how multiple intervals are handled. The two red boxes should move to the dotted red line and then stop. The two green boxes should first move to the red dotted line and stop, and then start again and move to the green dotted line and stop.
NOTE: The behaviour described below for the red boxes is accurate according to the SMIL Animation specification. However, I think SMIL Animation may be contradictory here. I will write up an explanation soon but until then and I might change the description of the expected behaviour of the red boxes.
The first box has specs begin="1s; 4s" and
end="2s". According to the algorithm given in SMIL Animation
the first interval is from 1s to 2s and there is no second interval and
there is no end time to match the begin time of 4s.
The second box is the same as the first except that it has an end
spec of end="1s; 2s". According to the algorithm in SMIL
Animation the first interval should be 1s to 2s and not 1s to 1s.
So this animation should behave in the same way as the first.
The third box has specs begin="1s; 4s" and
end="2s; indefinite". This creates a valid interval from 4s
to indefinite so that the animation runs twice. On the second run it is
not constrained by the end attribute and will arrive at the green dotted
line.
The fourth box is the same as the third except that it has an end
spec of end="1s; 2s". As described above for the second box
this should result in the third and fourth boxes behaving in the same
manner.