Below is an example of three timelines running in parallel, yet at different speeds.
<smil:par begin="startrace.click" dur="10s"> <smil:animateMotion begin="0" dur="3" calcMode="spline" targetElement="racefaster" values="20,0;300,0" fill="hold" keySplines="0 .75 .5 1" keyTimes="0;1" /> <smil:animateMotion begin="0" dur="3" calcMode="linear" targetElement="racesteady" values="20,0;300,0" fill="hold" /> <smil:animateMotion begin="0" dur="3" calcMode="spline" targetElement="raceslower" values="20,0;300,0" fill="hold" keySplines="1 .5 .75 0" keyTimes="0;1" /> </smil:par> <input id="startrace" type="button" value="Start Race" /> <div style="background-color:lightgreen;position:relative;top:0;left:0;width:50" id="racefaster">Start faster (keySplines="0 .75 .5 1")</div> <div style="background-color:lightgreen;position:relative;top:0;left:0;width:50" id="racesteady">Slow and steady (no keySplines)</div> <div style="background-color:lightgreen;position:relative;top:0;left:0;width:50" id="raceslower">Start slower (keySplines="1 .5 .75 0")</div>